As with most features of the game system, the focus is on the 80-90% most used mechanics. Unfortunately, Elemental Adept throws 2 minimally used mechanics into the mix: Minimum roll (which is different then existing reroll and only instance in PHB), and ignoring resistance (which is only mentioned twice in PHB). It's on the list of mechanics not yet supported, but no estimate of timing.
For the minimum roll aspect, I'd probably just fudge it and give my player +1 per die. It only changes the average damage by +0.5 per die rolled.
For the ignoring resistance, it needs to be added. One of the reasons why it hasn't been implemented yet is that "ignore damage resistance" type effects are actually 2 separate things: ignore resistance for all spells, or ignore resistance for a particular damage roll. Even the all spells can be difficult to code as a general rule. I'm guessing that per spell would come first to support NPCs too.
Regards,
JPG