Yeah, because clerics always run down the hall, through the door and around the corner headlong into an ambush without the rest of the party.
I don't complain about range, LOS issues. I just don't heal that person. I stick with the bulk of the party and if someone runs off or around a corner, it isn't my problem. It's theirs. I'm not dying to save some monkey on crack.
If they ask why I'm not tossing them heals, I'll tell them it is because they ran like a monkey on crack down the hall, through the door and around the corner headlong into an ambush without the rest of the party.
If you choose to run out of LOS/range of a cleric who is with the party, that is your problem, not the clerics. Carry a pot.