Well, such drastic changes would make the game totally different. I guess it will unbalance some warbands and reward close combat slaughtering instead of tactics. For example, close combat beasts like the vampire, or sweepers like a dreg/youngblood with two-handed or halberd would make exp as usual, but more tactic roles like a runner, a sniper or support spell casters wouldn't. So why taking a runner or a sniper at all, it will be better to make every hero a close combat specialist. Some bands are also designed to rely more on heroes and some others on henchmen for the killing, if you reward only the killing that last group of bands will have a tough time developing their heroes.
Same thing making henchmen easier to die, it will reward getting poorly equipped and cheap henchmen like naked verminkin, and penalize expensive and well equipped henchmen like swordsmen or big guys. I think it will also make your band likely to be crippled if you loose the first couple of matches, unbalancing the game in favour of bands who start strong and tend to fade, and penalizing bands who develop slower but end up being strong.
I think the solutions for the issues you may have are not in the rules. I don't think you need to change the skill system to prevent a strike-to-injury/resilent combo (not so impressive in the other hand), you just need a decent marksmen with a crossbow and that two skills could easily go OoA before even being used (resilent works only in HtH, so that hero would be vulnerable to shooting and magic missiles). Then if you want to prevent voluntary routs to get free exp, change scenario conditions, but not exp system because that will start whole new set of issues.
Tell us your feedback if your are playing under that house rules, it will be interesting to see how the game changes.