I really liked 3.0 type resistances.
Really.
I had no problems with investing in a secondary weapon. But I did not like the fighter beeing proficient equally with all kinds of weapons.
5/bludgeoning allowed the cleric to shine in those kinf of combats. It also allowed the fighter to shine if he did not invest solely in a single weapon.
Zombies having 5/slashing in 3.5 however was contraproductive.
On the other Hand I could imagine, that instead of 5/bludgeoning it would even work better with vulnerable 5 (bludgeoning, radiant) if undead have as many hp as normal monsters.
In 3.0 it worked well with DR, because undead had no con and generally low hp.