I'm not opposed to spending chump change for costumes. I event spent something like $5 for cosmetic DLC in Marvel versus Capcom 3. $5 in that game gave me costumes for 4 different characters. $5 in Marvel Heroes will buy you a shitty costume, but you'd need at least $10 for a decent one.
Again, I'm not big into FTP so maybe I'm lacking perspective with this stuff. My only real frame of reference is PoE, which I didn't give me these vibes. I have no idea how their prices compare to other 'free' games. But a lot of this shit just seems scummy to me.
It seems shitty that you're given a relatively abysmal drop rate, and that Magic Find bonuses you find on gear pale in comparison to the boosts you can buy with cash. Sure, they hand out plenty of them with free promo codes, but they come in so many different flavors that your stash space runs out quick. Magic Find is a mechanic I find distasteful in ARPGs to begin with, but here they exploit it for all it's worth.
It seems shitty to me that for a 'Buy 1 Get 1 Free' promotion, the free token you get is random. The odds of getting a 2nd character that you don't want, or a duplicate that you already have is very high. Why not just let you pick 2 of a particular tier? If you're going to ask me to spend money on your amazing deals, they could make it less of a gamble.
And yes, you can buy team-ups with eternity splinters. They cost at least 450, though, which is more than all but the 'premium' characters. Just seems out of whack. Honestly what tickled me there was the fact that their email was trying to convince me that pre-ordering a bunch of Diablo 2 mercenaries for the price of a retail game was a great idea.
There's just too much 'BUY XXX IN THE CASH SHOP FOR THE LOW LOW PRICE OF DERPITY DEEP' to not bug me on some level. I never got those feels from Path of Exile, but sure, this is a different beast. I'm sure Marvel wants to make their money where they can.