You can only house-rule out so many concept of
4e before it becomes you essentially only using the combat system. Then again, that alone would be a good reason, but there's plenty more technology to take advantage of.
Regarding the incentive to mindlessly charge into any encounter for XP: this has always been problematic for RPGs, at least as far back as I know. My solution has always been that if you overcome or effectively neutralize the encounter, you get the XP. If you talk your way out of a fight, sneak by them, or even manage to run past ambushers on your way to your main goal, you get the XP. Of course, if later you encounter that same group... you get to kill them for no bonus.
I think the treasure parcel system is too integral to balance to throw out. Weather you get it perfectly delineated over a single level is probably not as important as assuring that they eventually make it to the PCs. To give you an example, in my non-megadungeon adventure, I handed out treasure parcels from both level 5 and level 6 at the same time, until by the end of 6 I had exhausted both lists.
If you are adamant about cursed items, don't count them in the treasure parcels. Traps & Hazards, "disease" tracks if flavor modified, or some of the more malicious artifacts (think eye/hand of vecna) can fulfill the duty of cursed items. Perhaps as a reward for overcoming the curse somehow, the player is THEN rewarded with a magic item.
4th edition is not designed for inter-combat attrition. The fact that, given only a few minutes to rest, the party can reheal to full, you can't plink away at HP totals as easily as in earlier editions. This is to say nothing of the fact that a night's rest will restore all resources to the party, standing in stark contrast to older editions where a night's rest would provide, at best, a few hitpoints and of course the spells to heal some more of it back. The only resources that can be reliably drained over the course of a day are daily powers and healing surges, and those only force a rest. Of course, getting caught while trying to rest for the night when you pushed yourself to the limit could put the fear of death back into your party, but doesn't quite attain the feel you mentioned of being a penalty for wandering around.
Think of it this way: in old CRPGs you had the choice to wander around aimlessly and just kill easy fights until you were stronger and could take on the final challenges more easily, or you could rush to the end and, being at a lower level, experience a very harrowing fight. Why not let the players choose? Let them decide weather they want to stomp low level monsters or dig deep and bite off more than they can chew. Either can be fun, and like another poster pointed out, if things get out of control you can have two encounters crunch together to make something very scary.