MadOverlord.755: Yeah but isn't that sort of like going crazy looking for a penny in a couch cushion, despite already having $1000?
When you're talking about the "most powerful party", if you compared yours to a non-maximized party, would they really function all that differently? I don't see how it's "hurting the game", unless you genuinely couldn't beat the game because your party is too weak, not being maximized.
Different players play in different ways. Some players are really into maximizing their party, working within the rules of the game to create the absolute best possible party, while others play more "in the moment", adapting to each situation that arises and not worrying about having a party that's not quite as powerful as it could have been. For the first type of player, the rules in Lords of Xulima make optimizing the party tedious and not fun, but for the second kind of player, those same rules might make for an enjoyable experience of give-and-take during the game. For example, investing in the Learning skill means more XP in the long run, but maybe it's better to put points into different skills instead to help out in the early game? For a maximizer, more XP is more XP, so that's always going to be their choice, but other players might wish to increase their power early at the cost of power later.
Some games favor one type of player over the other. Many of the Might and Magic games are good for optimizing parties, for example (see all the threads on strategies for MM6 and later games), whereas a game like Arcanum is really bad for that since it's easy to make an overpowered character and the focus is more on intentionally playing "sub-optimal" builds because each offers a very different experience during the game. In Arcanum, oftentimes the most enjoyment is had by truly role-playing a character, complete with flaws and limitations, rather than trying to make the absolute best out of the game systems.
Personally, I tend to play as I go in most games, with some plan in place to create an effective party but without worrying about making it the absolute best it can possibly be. Usually this is fine, but the first and only time I played MM6 I was having a very tough time until I looked at some guides with some better advice for maximizing my party's effectiveness. It doesn't surprise me that that game in particular attracts players who enjoy that process.
For Xeen, the sense I get is that it's pretty easy to simply "win" it without worrying about one's party too much, but many players still find enjoyment in playing for a completely maxed-out party, or in setting optional challenges to tackle that are much harder than the game itself (e.g. clearing out the Dragon Tower early). But I've only played Xeen once, when I was much younger, so I'll have a better sense of that when I play it again (I need to play MM3 for the first time ever first, now that I've finally played MM1 and MM2).