Rito has skins
Rito has icons
Riot does not gain more people if they cannot even buy Champions to buy skins. Therefore, as "business-y" as it may seem, it alienates too many people. The prices on Champions is high, and so are the prices on skins. Odds are, from a consumer's point of view, its not looking so good.
Any who, on your point on "every game has something" its true, most games (to even all games) stand to reason of having you earn things (say Smash as an example or even Smite) but its never unreasonable. Smash's roster added in plenty of more characters to chose from, as well as Smite. I've never heard anyone from Smite ever complain about having a lack in characters. Its honestly Riots fault in letting things get so far out of hand. Players from Season's 1 - 3 had a better chance in getting all the characters than many now do. Point is, there were more than likely less than 100 champions then, and since then, Riot's added so much.
Poor decisions from myself aside, they never stopped to think what would happen if they never ventured beyond Summoner's Rift. They had the opportunity with Dominion... and just left it. They made a new map, Twisted Treeline but beyond that it only got one major update and nothing special since has been put into it. Not even a Team Builder. When Riot did bring in a way for players to create teams with ease, they took it away with no remorse and haven't even thought of it as a bad decision.
I've had a friend play since this game began, but now he's tired of it because of how Riot screws around with the system all the time. Another friend just couldn't keep up, coming in after I did and got overwhelmed. They periodically come in, and I would leave as well, but I'm almost done with these stupid champs. Its been almost 3 years now. Two and a half years of this game. They've only released about 15 champions since I've been on here, and I still am struggling to get all of them. It took me nearly two years to get half of the whole champion pool. Do you really want to say that this business decision will cause me to literally pay for these online characters?
I don't care if you down vote this. And I can tell by that icon that you have money to blow, so probably what I'm saying is fruitless. But, when Riot has skins, ward skins, icons, boosts, and plenty of other things (such as a merch store) I don't think I'm going to hurt a Riot employees paycheck if these champions were reduced in price.