I just dont see this being 'more interesting'. It runs into the idea that this more engaging simply because its more to do. As a point from my perspective, if youre not using Shadow flare on CD, you may end up missing a cast and hurting your overall dps. This isnt interesting to me as a mechanic, its simply "Press this button every 60 seconds", and to do that, you need to use something that you can weave with. There isnt much of an argument to say "Oh should I put off using ShadowFlare and hard cast a dot cause thatll be more damage." Only situation I can imagine where you might hold shadowflare is for damage windows, but if that damage window is more than so many seconds out, its not worth while to hold. This isnt any different than SE on DRK in this regards. I dunno if people would be happy if, lets say, they reduced the potency of Bio and gave you miasma back, so that both deal the same amount of damage, but now you have to manage two skills. More to do, but more engaging? Its like saying that to make things harder, just have the boss have more HP and better defense with nothing else.
I didnt play SCH in SB, and Im not going to say SCH right now is the most interesting thing since sliced bread, but Im just not seeing this position of it being that much better from a pure mechanics point. I guess if its just a matter of pressing more buttons ensure things are off CD, then yeah I guess. And I know you can boil that down to it broadly with any class, but I dont see much meta game here or actual thought process going into things that this system was that substantially more interesting. Shadow Flare off CD, press button unless youre within x seconds of TA. Simplistic PoV, sure. But I think saying that this kind of thing made a huge difference in play is a bit of a stretch to me.
This all being said, most of this can be fixed by adjusting almost nothing on the class and adjusting the fight mechanics in the game. This goes back to the issue I see generally is that a lot of complaints come from the fact the game has a low skill floor. Would SCH still be considered boring if you were required to cycle much faster through single target healing, aoe healing, shielding and using oGCD heals in a more managed way, and filling in the rest with Bio, Ruin, and Broil? Whre you had to rely much more heavily on hardcasting heals? I kinda feel this wouldnt be the case. But this requires harder encounters which requires higher skill floor. Heck, considering most players dont play savage, simply increasing the skill floor to be more healing intensive and managing your heals better would actually solve some of the complaints. Itd still be boring in savage, but for the average player, its gonna be more interesting simply because difficulty requires more from the healer than they would do currently.
I think that encounter design is the side of this equation that people rarely ever address. Its always "Its a class problem" and not "Its a fight problem". If the game had way harder mechanics that required more of youre input from the healing side, I dont feasibly see this being as big a problem. Maybe people feel itd be easier for the devs to change class mechanics rather than address battle mechanics.