I agree 100%, her initial rework was ultimately a stats nerf for a utility buff, IE her E and unstoppable ult. Shyvana's overall gold value is down due to the loss of her passive (unless you get 4+ drags 3 is only like a -200g diff not much).
The reason she was seen as super op was simple the power of the jungle and how much gold you could get very quickly, bringing her to her mid game status where her huge Q nerf was no longer a factor. Shyvana has a solid mid/mid late game, but suffers if her team dies a lot since she has no early game or even early mid game power to counter it, or b she gets invaded by the jung+ a laner.
My biggest gripe is not that Shyvana should be insane and oppressive, she needs to have weaknesses, but I want to compare only 2 champions.
Shyvana- Supposed to be tanky/deal dmg/ poor ganks and power farm/ nice AOE if they are grouped/ reliable but dodge able Initiate.
Hecarim- Is tanky, Deals a decent amount of dmg, good ganks, good farm, good AOE, if grouped, good gap close, nice mobility, reliable ult that is hard to dodge, sustain, good escape, scales well at all stages.
Basically all that shyv does + some
Lee sin- can go dmg or tank we'll say tank for now, so Tanky, deals decent dmg, great ganks , great farm/sustain doing it, no AOE, high mobilty, hard to use but reliable initiate/disengage/pick tool, sustain, great escape, scales great early to mid not so much late, but becomes more of a tank.
You can say apples and oranges, but in all seriousness these champions do everything Shyvana does + more yet she gets nerfed and lee gets buffed and hec remains unchanged.
Side note more nerfs to masteries incoming, guess who uses almost all of them. Hint? It's a dragon there now you have a 50/50chance.
Shyvana gets more indirect nerfs than Sejuani