Riot's profits were never the reason why a certain change was ever introduced to League.
And you also have to understand that League is an e-sport and that top tier play is very different than ours. So Riot has to do battle on two fronts - make out gameplay satisfying and as balanced as possible and then make sure that League is an entertaining e-sport to watch and engage in.
The constant complaints about their e-sport choices are getting tiring, when in fact they've already given an explanation why sometimes it may feel as they can lean in a certain direction. Not to mention that only 1-2 patches are actually ever oriented towards pro play and all of the rest are for regular play.
I still would like to see that data from 5.15,
as i can give you a lot of examples of champions not seeing any games at that point:

These are just the champions of the top of my head, the actual data might put more on this list + take away the 8 champions that didn't exist, prior to 5th of August, 2015 (patch 5.15 notes were posted on that date, which might be a day earlier than the patch but that doesn't make a difference). Marksmen were updated in the patch 5.22, ~14 weeks later and that means only about 3 Marksmen choices on the bot lane, with 3 support choices to compliment them. More champions that are on this list were out of the meta.
So that makes 126 total champions - 45 on this list = 81. That's 64% of the champion pool being used, by my calculations. Respectable sure, but those 45 champions are still someone's favorite champions that weren't on the map for various reasons.
Class updates and Keystones for the sake of "Meaningful choices" is another bullshit excuse...
Let me stop you right there.
One would think that class updates actually addressed the issues of a particular class and left the updated champions in a better spot than before. So your issue with it is that those champions gained popularity after the updates?
Isn't that the point of those updates?
To give meaningful choices when picking champions, making sure that each of the champions provide a unique strategic choice to a team and above all else feel satisfying to play with/against them?
Or is the issue you're having here why were the damage classes updated first and tanks/supports were left as last? One simple reason - people enjoy playing damage classes more than non-damage classes so Riot appropriately started the updates that reflected our preferences. Unfortunately for you, you were in the minority.
Riot has stated multiple times that they could change the pace regarding the VGUs/new champion releases when the community shows the interest in one more than the other. Currently, the data shows that new champion releases are valued more than the updates but there were 6 new champions in 2016, while there were 4 VGUs (if i recall correctly).
So that's really close to one another, still being 10% in favor of new releases based on our preferences.