Many, many games follow this same pattern - start out relatively fun and reasonable, quickly devolve into a number decrementing simulator; a timer-fest designed to annoy the player into coughing up money to make any meaningful progress.
Clash of Clans is the one that's at the top of the free charts right now, and its entire mechanic is based around this.
Perhaps the "free-to-play industry" needs some offending. Their entire business model is exploiting vulnerabilities in the human decision making process. It's exploitative and rotten.
I remember honest games. I want those back. Now even some paid games are infected with this F2P schlock.
ive a much easier analogy.
we'll let you start a shop. then at some point we'll ask you protection taxes. if you dont pay we'll make sure to make your life hell. You can also choose to close the shop of course, and change city/country. nobody's forcing you.
To elaborate: The customer is attracted by the "free" game and how fun it looks. They are then kidnapped by the addictiveness of the initial gameplay - before any significant payment is required. Then they are tortured with the unenjoyable misery of the free grind; Usually whilst they are reminded of how much better their friends are getting on in the game (yay social networking!).
But they are told they can pay to skip the bad parts. This is where I compare it to Stockholm syndrome: They are confusing relief from abuse with an act of kindness. They feel the same relative bump in happiness, but mistake it for feeling good, when it's actually closer to relief from harm.
And of course, much like Stockholm syndrome, they don't even realise quite how much they've been suckered in. They just think "that was fun" - or in the case of the real syndrome, "they were justified" - rather than realise they've just had thousands of dollars extracted from them while they were held captive...
[1] https://en.wikipedia.org/wiki/Stockholm_syndrome
EDIT: I realise this may be a bit offensive to those of you who work in the free-to-play industry. But as a gamer, I really do wish the industry wasn't trending this way. What's wrong with paying up front? I'll happily pay large sums of money for a game + expansions. But try and nickle-and-dime me and it ruins the whole experience.