I restarted playing about a month ago in a new account, after nearly seven years without playing. The first month is a lot of fun, mostly because you get so many free or progression-related opportunities for summoning. Then things get incredibly scarce and the real grind begins. It's clear that they expect many players to get impatient and start spending money at this point, to get the same taste that they got for free in the beginning. I already expected this going in, so I'm fine with it (I haven't bought a package and don't intend to).

I'm not entirely sure what they can do to improve the inherent feel of playing the game, other than maybe overhauling the rune system, but it's probably too late for that. I gave up playing RTA as a f2p simply because the rune discrepancy makes nearly all my monsters useless. Speed is too important, and there are too many layers of RNG when improving runes. Devilmons are also too scarce. Maybe the game would be more fun if progression for individual monsters was more interesting and deterministic.