Feel free to correct me but it seems like Doremi and 9ml may have had the largest impact on what the style of design Blue Archive characters were eventually going to have from the first year onwards I think.
Even Mx2J started to slowly remove details and kinda "flatten" his artstyle to match the trend more and more and I think his designs suffered for it, of course there were other factors that had more of an impact obviously but you can see the progression or I guess in this case the regression when you look at his section.
I kind of hope artists like NAMYO, whoisshe and many of the other artists come back for their own character(s)' alt rather than the alternative.
In my mind I remember Sumire's alt looking kinda underwhelming compared to her base.