Woah. With the right domains, clerics can exceed fighters as aclose combat monsters.
I think that the problem you might be facing is that you're *stuck* in thinking of them as healers and thus aren't seeing all the other possibilities. The new spontaneous casting ability means that most adventuring clerics (usually neutral or good) can blast away with their offensive spells (often pretty decent, I mean Flamestrike ain't bad), can buff like mad (and this is where clerics get really sick, as well as enhancing the entire party anyway), can do utility spells of all sorts *and* can heal like mad. Your rogue with a wand of cure x wounds will *never* match up to a cleric, bceause the cleric can cast the really good stuff like Heal and Healing circle, and the cost of wands for the rogue is rpetty high, not to mention that he a) spends time he sdhould be doing other things like sneak attacking on healing people instead and b) needs to make those Use Magic Device rolls. By the time he gets to a high enough level that Use Magic Device is particularly reliable, the cleric is a powerhouse anyway and still outdistances him on healing. Then there's undead and outsiders, against which a cleric is particularly good.
Let me put it this way. If your rogue with Use Magic Device is so good and replaces the cleric completely, then why aren't bards, who can do the same, and can also cast healing and some buffing, far moer popular than clerics?