Should have clarified a little, I was trying to answer both you(experience) and the OP(money for rewards) with the same sentence.
In a sense, players spend because on micro-transactions because they think that the purchase would improve their experience with the game. As OP points out, there’s often no point spending in events that give you rewards that are easily worse than what you can straight up buy with cash. It is ultimately the player’s decision if they want to spend on events over straight up buying the character because they have that information at hand.
In the regards of having a crappy experience, it ultimately boils down to how the micro-transaction is implemented, as well as each individual’s subjective feelings towards it. For me, I never spend on micro-transactions. I’ve seen bad implementations of it(Walking Dead RTS, Honorbound, Maplestory), and I’ve seen good implementations of it(Halo 5, Fortnite, Dragonnest). In general, it does ruin a player’s experience if it’s not implemented well, but it is still optional at the end of the day.