wow. vanishing dyes on legandaries? after, ... hmm after 8month. That is quite a proof of bad game design if you are not able to implement the possibility of disabling a texture.
As with most things related to game development, it is always much faster to talk about changes than it is to implement them.
The Vanishing dye for legendaries has been the most frequently requested dye for legendaries by far, and this is maybe why people tend to overlook that we actually also need to make the other dyes work as well. It is not simply a matter of just disabling textures, in fact all the textures on all legendaries will have to be redone so that dyes will work on them... this is a massive and rather time consuming task as you can maybe imagine.
Honestly, and? I see far too many of these Blue posts that chalk up their tardiness and sluggish updates to 'game development takes time!' Even when responding to concerns addressing purely cosmetic changes, you still throw out 'it takes time!!' and people seem to accept it. To me, it seems the only thing that takes time are the corporate hoops you have to jump through, and instead of just outright saying that it's because Blizz is now a corporation instead of a dev, you haphazardly state stuff takes time.
There's been a limited amount of cosmetic/visual updates on this game since launch, despite a massive amounts of concern. Since you stated that these things take time, I went through the league of legends patch history since Diablo 3's release, and picked out only cosmetic-related improvements (not Skin additions as this would be biased in terms of their microtransaction businessmodels.)
Summoner's Rift graphics update
Ashe model update and art update
Art overhaul for several champions
Art overhaul for Ashe, Cassiopeia, Ezreal, Kassadin and Mordekaiser.
Model and art update for Katarina.
New splash art for Miss Fortune, Morgana and Tryndamere
Added new particles to wards.
Updated lore and graphics for Soraka
3v3 Twisted Treeline Complete Remake
New Splash art for Brand, LeBlanc, Master Yi and Mordekaiser.
Nidalee visual update.
Along with 12 entirely new champions developed within this timeframe, with their own skins, artwork, etc. Yes, the businessmodel they're adopting caters more to a frequent update routine, but even if that was the incentive, it's evident from the results that is enough for them to push out way more content way faster than you guys.
And this is done in a free-to-play game by a company with less resources and that's far less established. When stuff like this is being done by competitors, I just get annoyed when a company like Blizzard throws out patches with marginal change after marginal/trivial change, and then justify it by saying 'game development takes time.'
I know it's far more work than I realize, it's just that, everyone else is doing it, except better, more and faster, so, I dunno what else to think than that Blizzard has become the tortoise of devs.