For many mid-to-late game players the only reason to do summons is for the hero of the month. As you get farther along in the game, and especially after you’ve built a couple of tc20s and gotten the event heroes you want, the marginal value of new non-HOTM heroes is very low.
It would be great if SG offered HOTM-only summons. Right now the odds on an epic or event summons are somewhere around: 16-25% 4 star, 3-5% 5 star, and 1-1.5% HOTM. Perhaps SG could offer something like a 300 gem HOTM summon that gave a 6-10% chance of the HOTM and a 90-94% chance of a random 3 star.
I am a cheap to play player. I would happily spend $10-$20 per month, but I now spend less than that because I have most of the 4 star heroes I need and the odds of getting 5 stars and the HOTM from epic and event pulls are too low to justify the expense. I will wait to get my 5 stars from my tc20s, even though doing so means I give up chances at the HOTM.
If SG offered higher probability, direct shots at the HOTM though, I would definitely spend the rest of that budget every month. I’d imagine that there are plenty of others that would do the same.