For clarity's sake :Saying "implementing as a feature" is the exact same (for my point) as saying implement it as a pack -as the point argued is not the fact they cant make money on it (buying two skins = more money for the skin switching side) but that it would invalidate the niche of ultimate skins.
Okay once again... I reiterate that the changing form aspect of a skin is specifically associated with ultimate skins, anything else (sona's music etc) is an addition. Do you seriously think I am the nearsighted one when I'm literally using something Riot has stated before in order to make a point.
If i were to explain everything in full detail I'd be here all day. Probably more so because you don't seem to understand how product niches work. You can think and propose an idea (this idea has been voiced several times before - I've seen them and the arguments for and against it) however when someone says it is not viable and gives a valid reason for this then instead of trying to beguile that person you could actually make meaningful counterpoints.
Now For your other point that you made in the other post:
Riot or any other company do not 'need' to make fail-safes for user error / user issues like lag etc (they of course do this anyways which is appreciable).
For example GUMI - does not refund / replace something lost due to a user being silly.
Now when thinking of the skin switcher feature what are the inputs and outputs?:
The main input is time, money and resources.
The main output is that people can switch skins mid game (possibly monetary returns based on skins or the feature itself).
This results in the question is it worth making this feature?
option 1 means making this feature available to everyone because it would be used as a failsafe for people who couldnt pick a skin, due to lag etc.
option 2 would mean people would have to buy this feature: this means riot gets monetary return on this feature but the community has to pay for the failsafe method (possibly becoming something the community becomes irritable about).
In likelihood the making of this feature is far too likely to incur more detriments that positives (both gameplay-wise and community-wise).
Also the making of this feature will pull resources from projects which actively advance the game: aka new champs, champ reworks, skins, balancing, bug fixing etc. All of which actually incite people to play more and spend more with little outcry from the community - though outcry is inevitable with the number of people playing.
So in short the feature you are proposing is nonviable in its current state (primarily because of the way the client functions).
And btw in your OP you stated specifically "evolve" between skins.