It's funny, but sometimes it's the exact contrary that happens to me. The most recent example might be Lands of Lore Throne of Chaos. I loved that game back in the day, but it owned me on a regular basis.

Bought it on GOG and so far, I'm doing far better than before. Not that the difficulty has changed, I think, but simply that with my past as a gamer, I acquired some "survival reflexes" in other games that are particularly suited for LoL: save very often, always compare items and don't always equip the most recent one, look everywhere for secrets and hidden traps... Eased my progression a lot!

You also have to love how the map/view screen in all RPGs of a certain age was only one quarter of the whole screen.

If I am replaying an old game I often play on easy. Usually I'm just there to relive the experience, not grind it out. Fallout 2 is a good example.

Usually I have no problem replaying an old game, but trying an old classic is another matter, sometimes the games do upset me.

Replaying the very oldest RTS games like Dune 2 or Warcraft (1) made me wonder how on earth I could ever stomach the clunky controls and interface. But then, back then you just didn't know or have anything better.

The controls and user-interface in e.g. Warcraft 2 (BNE) are "good enough" for me, as far as RTS games go. Age of Empires 1 is a borderline case, the Rome expansion pack at least adds the very much needed "find inactive peasants" button. For some reason I didn't feel the need for that in e.g. WC2.

With many old games I miss a good tutorial which teaches me how to play. This was true already back when these games were new. Just trying to figure out how to play Master of Orion or Master of Magic seems such an obstacle, as if you'd have to memorize the manual before you start to play. Same goes for many flight sims, thus I always favoured WW1-WW2 era flight sims with less controls (some of them played more like glorified 3D shooters, e.g. Red Baron), not modern flight sims like Falcon series. I did play Falcon 3.0c quite a lot mainly because I had paid good money for it, but it seemed all those weeks or months I was still merely trying to learn to play the game properly, not really playing it to the full.

Another thing are those old games where the user interface is full of odd symbols which are trying to represent something, and you have to memorize what exactly each button does. I'm looking at you two, Populous and Lemmings. For some reason quite a few Amiga games (or PC ports of them) seemed to be like this. Maybe Amiga games favoured symbols instead of clear English text because their main market was apparently Europe, with various different languages.

ARX is a great game, no doubt about it. Back in the day I logged a ton of time in it too. But I maintain that the controls suck. Like the fact you have to be sneaking to be able to just click on something to pick it up. Otherwise, you have to drag the thing to your inventory. And the magic is cool with the hand casting, but again, it adds another 'mode' of input where keys do different things. Maybe there are shortcuts around these things, but like I said, I don't have a ton of time and am just trying to jump back into a game - I don't feel like spending three hours getting comfortable with the controls, only to have to do it again two weeks later when I find another chance to play.

Well to pick something up, just hold shift and select the item. If you see a weapon that's on the ground and you want to equip it, just hold Shift and F when you pick it up. That makes it so you don't have to hop into sneak to pick the item up. Yea if your not aware of the shortcuts and hotkeys, then I'm sure it would seem like a game that has some pretty bad controls. Have you ever played Dark Massiah of Might and Magic? It was made by the same developers, Arkane Studios. They make some pretty awesome first person combat fantasy games. I keep a close tab on what they do.

I got WC as part of the battlechest and never really played it. The biggest irritation I had was the tiny view I had on the game. Granted that was technologically required at the time, but it made it very hard to play the game compared with WC2. WC2 though stands up fairly well when compared with WC3.

Happens a lot.
Just the other day I had a real hard time getting back to Fallout! Amazing game as it is, the beginning dungeon was sooo ugly and the movement so klunky and the control scheme so awkward I almost quit right there. Actually I did quit right there, but then restarted. A bit further on and the senses got readjusted, everything was pretty neat again and the wasteland was alive!