I think it really depends on the DM's playing style. My group has had to learn what the DM does in combat, how he handles skills, which ways his rulings fall...etc. If tHP is so important in your campaign (I can't really know why, but I'll guess) maybe you're giving them too many surprise attacks, or hitting them with large creatures that easily bypass their AC. Or maybe everyone wields 2-handed. When I made a character concept and put it on these boards about a year ago including that feat for a Cleric/Mage/Mystic Theurge everyone gave me crap about it saying there is much better stuff out there. I guess they're right in their own way. If the party's combat philosophy is everyone take care of themselves then having everyone take this feat sounds good. If the philosophy is everyone have rediculusly high AC or lets deal 271 points of damage in the first round, then there are other divine feats that are better for them. I personally (as a player and a RPGA herald GM) wouldn't change the feat just because your player's are wising up to your tactics. That really just breeds anger, and feelings of unfairness. If it's becomeing such a problem for you change up your tactics. if the movement is hurting you, have them fight some flyers. If the extra hps are hurting you, counter it by going around those hps. Death attacks, petrification, paralysis, mind control, etc. Or you could fire-ball them to death instead, assuming that their reflex saves are the lowest.
In my experiance, as a Paladin, I need to get into the fight ASAP. Every spell I cast, everytime I need to call my mount, and every standard action I use doing this delays me from my job: killing things before they inflict damage. (of course this is my combat philosophy). I've never taken this feat, and none of my character development plans feature it before level 15: there are just too many other good feats that I usually have to take first: weapon focus, power attack, cleave, mounted combat, divine might, spirited charge, extra smiting. My clerics are always too busy buffing to do anything else, although I could really use the extra speed from this feat to extend my healing range (but then isn't there a feat in CD that allows me to cast cure spells at a range?).
In summary, depending on how your players stratigise to counter your DMing style, different feats will be over emphasised. If you want to de-emphasise those feats, you should look to how you DM first before changing rules.