I’d always say that any house rule that is proposed should be duly considered, but if it is inserted, the players and GM should come together honestly and discuss its effect on the game to fairly evaluate it. Otherwise there probably will be bad feelings for the reasons listed above….

Let’s say you play D&D 3.5, and decide to combine Move Silently and Hide into “Sneak”, and you also combine Spot and Listen into “Perception”. You also combine Open Locks and Disable Device into “Burglary”. Sounds like a simplification, but suddenly the Rogue doesn’t have to decide if he wants to be “traps and locks” style, “face” style, or “sneaky” style; he can be all three at once. To counter this you could reduce the Skill Points available, but at this point, you’re rewriting large sections of the game just to simplify something.

That said, the skills simplification of Pathfinder and such are a bit different; they’re intentionally rewriting the game.

Swordgleam: Pretty much; supplemental rules can swing both ways. As to your other note, IIRC, one version of Rolemaster that I played back in the day actually did have fire-building and cooking skills.

I use supplemental house rules all the time. In my current 4e campaign, I’m using a version of the “drama point” mechanic in some other systems to represent the favor of the gods (for the divine characters), the power of the dragonborn race (dragonborn warlord), and luck (ranger who rolls poorly). It’s more work for me, but the players love it. So far, no problems.

On another note, your point about characters suddenly becoming incompetent at basic skills gave me a great mental image of these guys sitting around a campfire happily, and suddenly being overcome with confusion about just how to cook their meat.

I think this happens more often than we think — and as I’ve said before — I think is the source of many so-called criticisms of certain games on message boards.

These players have tweaked their home game to such a degree that when a new supplement or variant comes along (especially with D&D) that derives its mechanic off the core rules — and not their table rules — it plays as “unbalanced.”