I think Jakub is more appropriate than me to answer this question because I never built EPEL but, as far as I remember, from a conversation with Jakub, he was doing major upgrades of odd versions.
Mainly because a major version is going to be there for ~1 year and that gives a little stability to the users of EPEL.
If what I said is accurate, the lack of 1.17 on Fedora is what made this scenario.
Nevertheless, Go 1.15 doesn't have support anymore from upstream so I would say that we should upgrade it.
I have no problems with trying to upgrade it to 1.16 or 1.17.
What do you think?