I think saying they 'need' the memory is just part of being part of an applications person/team! There is some ego related issue for IT people and resources e.g. "I must not be a real man if my SQL server could function adequately with 8 GB RAM and 2 CPUs"
I feel your pain, but as the infrastructure guy, you may be the one who has to reign in the teenagers!
Best case scenario: reduce the RAM and closely monitor SQL performance. You may need to increase again if those 60 minutes prove to be a problem. My bet is that you can actually get away with much less RAM for the VM.
Other ideas (which will induce swapping - so be careful) might include creating a Resource Pool with a limit of the amount of RAM you want to assign to the SQL Server, but allow the SQL to have the amount of RAM the dev's want.