It's a way of making more cash unfortunately. Games companies like Rockstar, not content with the 40 odd quid from each sale, saw a gap in the market and charged right in.
On the plus side, especially as a PC gamer, the extras you can buy are cosmetic mostly and don't effect the game play. PUBG, Rocket League etc etc are all perfectly brilliant without the added extra content. In Rockstars defence, they do release free content on a massive scale compared to other games companies.
All of the modern games I have tried, from The Division, great idea ruined by Ubisoft, to Battlefield 1, great game ruined by the recent patch, all have micro transactions.
Looking forward to Star Wars, the beta was not bad, Sea of Thieves and Red Dead 2. The first 2 of these will have cosmetic do-dahs which I can do without but Red Dead 2 will pull me in probably, who doesn't want to dress up as a cowboy?
All AAA titles will have extra content. It's the way of the world.
Oh
@foetus, GTA Online is a great blast on a PC with loads of mates. The clan/ group I have been in since 2000 all have it and we have some right drunken race nights.