I always got the impression that the healbot cleric was a combination of an old way of approaching things and an after effect of blaster wizards, S&B fighters, and sneak thieves.
I think the more important part here is it's a sub-optimal response to sub-optimal tactics from the rest of the party. If the party opens up by casting a solid crowd control spell, with the fighter running in to obliterate something with a THW charge and such, then the cleric might have more room to buff. Alternately, if the cleric had a bit of foresight, he would have buffed right before the fight, so he wouldn't have to waste precious combat actions. But instead, the wizard throws out a Fireball that hurts a bunch of monsters but leaves them standing, the fighter charges and hurts a monster (but leaves it standing), and the rogue does some piddly damage. Then the monsters act and mess the PCs up. Now, the cleric is wondering if the PCs can even survive a round without healing.
So, if the party opens up like the first half of the example, the cleric just doesn't have the need to heal in combat. Or if he does, one of the players is likely to say something OOC.