You know, attitudes toward house ruling is something that I've observed changing over time. Me and my current group discuss this since we've noticed several trends in house ruling over the years and I'm starting to house rule my 4E game.
In the 1E days, house rules were often used to make the game playable, according to the tastes and preferences of a particular group. Most commonly, you used alternate ability score generation methods. Other little touches were usually put in to make the game less lethal (like re-rolling hit points or something like that). But the truth of the matter is that in 1E, no one really knew the rules as written all that well. We just read the books, made characters, and played. If we didn't know something, we made it up and kept the game going.
In 2E, many DMs house ruled in order to tweak the game to fit their setting. In many ways, 2E was one of the most interesting times to play D&D because many DMs spoke of their games in terms of creating an ongoing narrative or at least a shared setting. Many DMs house ruled simply because they wanted to change a basic premise of the game in their own setting ("elves can be paladins"), or because they wanted to adhere more closely to a preferred milieux ("clerics of the war god can use swords.")
When 3E rolled around, there was a major shift in attitudes towards house rules. Most players and DMs were willing to accept additional options (new feats, deities, magic items, spells, et cetera), but seemed resistant to fundamental changes in the rules themselves (methods for determining initiative, hit points, weapon damage and the like). Many espoused a viewpoint that the rules were now carefully balanced by a large and diverse body of professional game designers, and with this perception of quality, were loathe to make changes. Even when dissatisfied with certain rules (grappling, attacks of opportunity), they generally played by the rules as written and ignored what they didn't like rather than trying to house rule it.
Now that 4E has come around, I'm noticing that most 4E groups are splitting into one of two camps. There are those who handwave anything not covered by the rules, either letting the DM adjudicate something on the fly or dismissing the incident in question as not being something that adventurers worry about.
I'm in the latter camp, the one who feels that the 4E rules aren't quite complete enough to be intuitive, and I sometimes yearn for a bit more procedural detail to avoid butting heads with players at the table. I played an entire campaign through the heroic tier and into paragon before I started house ruling.
In my new heroic campaign, I've got the following house rules:
• Attacks have no effects other than those listed in their rules text. Page 42 of the DMG has caused me alot of trouble. I've had players throwing page 42 in my face for "actions the rules don't cover" to justify attempts to decapitate/dismember enemies, lasso and trip enemies with a spiked chain, disarm enemies, make called shots to the nuts, and use a shield to surf down a staircase a la Legolas in that cool scene from the Two Towers. That information is supposed to be advice for the DM, not a carte blanche for players to make up powers on the fly.
• Critical hits inflict the damage rolled on the dice +10. My players just don't have their max damage values figured up and it really slows down the game (typically, it takes the player thirty seconds to an entire minute figuring up their max damage). Hence, I instituted this rule mostly to speed up play. I've noticed that it also has the net effect of making monster crits more satisfying (which don't really scale up, since they don't get extra damage dice from magic weapons).
• Solo monsters have reduced hit points. Mostly a personal preference thing, but I'd rather have solos be dangerous for their damage output rather than their high hit point totals. At a certain point, the party is down to at-wills and it becomes a slugfest. To make solos more satisfying to run and more dangerous to the party, I reduce their hit point totals (usually by about 20%) and then give them an extra attack they can make as a minor action or something.
• Minions are tougher. I can dig the idea of a squishy minion, but 1 hit point is just too squishy. My players usually feel like minions are speed bumps or consolation kills rather than genuine challenges. Right now, I'm giving minions 25% of the hit points of a comparable non-minion, because four minions are equivalent to one normal monster, and rolling flat dice values for minion damage. My players enjoy minions this way because they sem to be a credible threat.
