I think it's less to do with some people not doing something right or wrong in the races, and more to do with the fact that the game suddenly switches into a racing genre despite the majority of the game being action-orientated. For me, personally, I really dislike racing in non-racing games because it's not a genre I enjoy. At all.
It's a bit like that for me too. When playing the GTA games I usually have a hard time completing timed driving missions that other players are hardly bothered by, and when playing games like UT 2004, UT III and Quake Wars, it seems like vehicles make other players more agile and me more clumsy. In Rage, I quickly hit a wall when it came to doing the driving delivery missions too, even though I didn't have any trouble being effective on foot. But trust me, the Reaperski missions in Giants ARE very doable! And there's only four of them. Maybe you won't enjoy them, but THEY won't rule your game. You'll get through them!
I do feel the game could've used difficulty levels, because at times the difficulty seems a tad unbalanced. I recall having a lot of trouble at one point during a mission with the Meccs (forget which one), and I must've died like a dozen times in usually the same circumstances. My jetpack didn't last long enough, or I was obliterated before I could make it to the next checkpoint/ / back to the healing shack. I suppose the fact that they don't have a limitless supply of healing makes the game a bit frustrating at times, too.
I really wish they hadn't included the cheats, and then whipped them back out after an update. I still haven't finished the game.
I suppose they wanted to challenge the players, and this way the game really forces you to think. Sometimes outside the box - to great success!
But, I agree with you. They should respect that every player is different and have different ideas on what's fun and what's not. If they're afraid that the players would abuse quicksave or cheat codes, or play on a difficulty level that's too low to be give them a proper challenge, they could perhaps put in some warnings that strongly discourage the players to make their games too easy.
However, I actually think that it's possible to indirectly alter the difficulty, and that's by altering your playstyle, at least in the normal missions where you have all time in the world to make your attacks. The more methodical and patient you are, the easier the game will be. Up to the point where you practically never have to take any risks. Snipe one enemy at the time, make frequent visits back to the smartie shop to get Healing Packs, take time to heal your squadmates and yourself with the Repair Gun, close in on the enemy valley from different directions weaken it as much as possible before you close in on it. Never rush.
You're saying that it's frustrating not to have healing in infinite supply, and that probably means that you're missing out on some very important knowledge about the game, because you do in fact have a never ending supply of health!
Ways to heal as a Mecc:
-Stand inside a Smartie Shop (this source runs out)
-Use a Health Pack, either taken from a dead Sea Reaperman or bought from a Smartie Shop (and the Shops DO have an unlimited number of portable Health Packs, meaning that the amount of "standing inside healing" doesn't mean a thing!)
-Heal by killing Rippers
-Repair Gun (as I didn't want to risk reading spoilers, I waited with reading the Mecc walkthrough until after I already had finished the last Mecc level, and that was when I learned that you can heal yourself as well as squadmates and buildings with your Repair Gun! Just shoot with it in the sky or on the ground and your health goes up - in other words the Repair Gun is another portable source of health that's also infinite, even though suppose it isn't fast enough to use in the heat of battle).
It took me some time before I learned to use orders to keep them outside of unnecessarry danger, but eventually I learned to that don't live long if you let them fight long range sniper/rocket duels with the Sea Rapermen, while they're a lot better at both killing and staying alive when doing machine gun skirmishes at closer ranges. However, their health were often weined down over time, as I didn't choose the Repair Gun as my backpack item very often. Now that I know that you can repair yourself as well as your squadmates, I suppose the Repair Gun is a more attractive choice.
But my usual choice of backpack item, the Forcefield, is perhaps still better than the Repair Gun. Sure, it won't directly keep your squad mates alive, but it does indirectly. When activated, the damage you take is so diminished it's almost silly, and thus you can do downright suicidal things with the force field on. When I said that it indirectly helps keeping your team mates alive, I was thinking of the usual Forcefield tactic: Just leap into the fray with all enemy guns on you! Just run into a small but heavily fortified valley with the shield up and your team mates in tow and kill everyone before the shield runs out!
That force field frenzy tactic isn't viable in a bigger valley with snipers and turrets, though. In that case, you wouldn't be able to kill everyone before the force field runs out, and the long range rockets and sniper bullets would make short work of your mates. When dealing with such a situation I would instead recommend that you tell your mates to wait in safety as you deal with the snipers and turrets yourself. You do this by popping out of cover with the force field on, shoot down an enemy or two and take cover again to reload your shield field. If you're good at multitasking, you can even destroy turrets and rocket reapers without any cover - just activate the shield when an enemy rocket is about to hit and quickly turn it off again. That way, the shield should reload more quickly than you can use it. The bottom line: You're nigh invncible when you're protected by the force field, and it actually drains energy rather slowly and recharges rather quickly even though it is so great. It's just unfair in your favour!
And one more hint: While the Shop only gives you 8 sniper rounds when you visit it, you can pick up as many as 12 or was it even 15 from the ground. So why don't you grab a sniper rifle (with 8 rounds) in the shop, drop it outside, grab another and then pick up the one that you left lying outside. That way you get to carry more ammunition. This can be done with all weapons that you find in shops during the Mecc and Sea Reaper adventures. It might sound a bit tedious, but especially when it comes to the sniper rifle I think that just a few rounds can make a great difference. Sometimes the sniper rifle is the only way to safely deal with something dangerous.