You can still heal in Cleric Stance and you can still DPS out of it. It is much less efficient and not as useful, but you still can. And if you are having trouble with fights with 5 seconds of being locked out of healing than that is on you and your team mates. Nothing in this game requires you to be healing more often than 5 seconds at a time, and most things in this game do not require ANYONE to be at 100% health.
You are asking for the healing role to be made easier, why? For your own selfish reasons. Its silly that you think your reasoning is more sound than anyone elses, when it just isn't. You give examples of a tank doing what they can do, and literally talk about how healers are comparable but try and state that somehow a healer has it worse off and that they CAN'T do something that they literally CAN.
A tank can still do those things, yes, but they are not as effective. The reason Cleric Stance is HARSHER on a healer is because a healer has no rotations. For the most part. And a tank who is in DPS stance all the time will generate tons less enmity than those in tank stance. They don't lose the ability to generate it, but they aren't great at it. However a healer DOES NOT lose the ability to heal or DPS depending on CS. Stop saying they do.
Also, with the use of cooldowns, HoTs, and fairy one can do most content while permanently in Cleric Stance. Most things do not happen suddenly in this game, and if they do you always have time to switch and heal, or throw out an insta-cast. Get use to the lag, don't ask for it to be changed or removed.
Besides if it was changed you would be in here complaining you accidentally de-activate it all the time and have to wait the 5 seconds to reactivate it. lol Also what does any of this have to do with a tank being lazy? Healers have to pay attention to fights too. Like wut. If you aren't paying attention and get surprised by things often that, is again, on you not the game.