There's a few important things to understand here:
1) Whoring healing is only good if the DM lets you take extended rests all the time. If he is, he is "doing it wrong". If you have to go through 5 encounters, you're better off having a more balanced party which can take down the monsters more quickly. Of course, this is still a symptom of the five minute workday, which, while mitigated a little, still can exist if the players choose for it to.
Incorrect, short, not extended, rests allow for massive heal whoring...level 8 cleric in my party has a "take your surge +20 power" during short rests, practically makes the surges meaningless.
Also, an extra healer ridiculously ramps up the healing in combat, not in extended rests. Do you even play the game? Extended rests give back daily powers and all health/surges, completely irrelevant of 'whoring', don't even need a healer for that.
2) If everyone has healing powers, then it may not seem very tactical. If you have only one healer in a party of 4, it becomes much more tactical, as it does if you have to go through five encounters per day.
Yep, but no way to force a party to have only one healer, eh? So much for tactics, then. My players trivially go through 5 "level +2" or more encounters without being low on healing...oh wait, two healers in the party (not counting the pseudo-multiclassed cleric), game doesn't work as designed, since not playing like the devs, I guess.
One thing that helps mess up the PCs is suddenly changing targets mid-stream after using several area attacks; basically, you beat on someone while simultaneously dropping AoE powers on them...PCs to "waste" healing as the suddenly healthy target, who they thought was the primary, now is more difficult to kill than someone else and thus they may have healed them for more than was necessary.
Alot of confusion here; my players certainly aren't so stupid as to do that, anyway. Once a player is outside of bloodied, really no reason to spend healing on him.
I've read this paragraph through, twice, and no, this isn't a viable tactic at all, at least against semi-competent players.
Hydras are "well designed" in the sense that they get around a lot of the problems other solo monsters face (particularly stun locks) but suffer from not having enough options.
And, you fail to mention, woefully insufficient damage. Hydra is also vulnerable to blindness...but really it's the stupid weak damage that's the problem. All my solos and elites have x2 damage as a matter of course (sometimes bumped to x3), still not really enough to do anything, but at least they can inflict decent scratches, over time.
I'm guessing you haven't played much past level 8 or so; the amount of healing at this point is positively ridiculous, and I totally have to make the monsters vastly more difficult than they are 'supposed to be' in the MM to even come close to keeping the encounters semi-challenging.
Yes and no. The game itself is pretty simple.
Actually, just plain 'no'. Dude, seriously, I have 10 models on the board (6 players, 4 monsters), and 20 different effects going off and on like Christmas tree lights, and that's not even counting terrain. Off, on, off, on, off, on, different intervals, some random, some stacking, some overlapping, some mattering on my turn, some on the player's turn...sure, each individual effect is easy, but that's like saying playing piano is trivial, since you're never hitting more than 4 or 5 keys at a time, each key makes only one well defined sound, and any idiot has enough fingers for that. I trust you don't buy that every human being is a concert level pianist.
Ok, perhaps you don't get the piano metaphor, so let's look at other games. Let's go over to Battlelore, another tactical miniatures game. 100 models on the board...and at most 3 'single turn' effects going off, not counting terrain. Ten times as many models, and yet much more streamlined.
Let's go to Quatre Bras, hardcore Napoleonics game...still has nothing on DnD4.0 after a few levels, with only a few situational effects in play at any given time...tired, exhausted, hidden, formation choice, leadership, in command, maybe I missed one. Maybe. Still not a couple dozen.
Mechwarrior? Uh, pushed, used last turn, artillery incoming, heat...might have missed one.
WFB? Routed, a few spells that linger...again, I'm not counting terrain effects, since I didn't in DnD4.0.
I'm hard pressed to think of any game with so many situational effects going off like this, effects that 'consistently' go in and out of play turn after turn.
We're talking a game with 10 dolls on the board, and a couple dozen effects to keep track of, not even counting powers and abilities and terrain and tactics.
No, no way, no how, can you call this 'streamlined', much less 'more streamlined than Dungeons and Dragons'. It doesn't matter if it's 'standardized'...it's nuts just how much of it there is to keep track of on a round by round basis.
I don't know if you've ever played the board game Arkham Horror, but it is somewhat similar in principle; the game itself looks incredibly complicated because there are a huge number of pieces, but the gameplay itself is easily comprehended.
Used to own an old copy of Arkham Horror (at least, if that's the board game with monsters wandering the streets, and you're primarily putting down elder signs to win)...Dude, no way you can compare the two, unless you've got 20 monsters going in and out of the buildings, each with random effects, that randomly shift around from monster to monster to player at random intervals.