High potential for abuse? Based on what?
The argument is that people are willing to break the law to get marijuana, so that constitutes a high potential for abuse. In any case a move to schedule 2 is long overdue, and clinical studies can provide the necessary evidence to further move marijuana to more appropriate classifications.
But what's the rationale for saying there's a higher potential for abuse now than before? Because some states legalized it and it's more readily available and accepted socially now? That seems crazy.
It doesn't indicate that the potential for abuse is higher. Schedule I is just saying that there is no legal use for this drug and it's highly prone to abuse, Schedule II is saying that the drug has accepted medical uses and can be prescribed but is highly prone to abuse.
Current Schedule II drugs include cocaine and morphine, for example. Things that you can receive a prescription for, but only under highly regulated and very specific circumstances with non-renewable prescriptions.
EDIT: Given that we don't have Dr. Feelgood's Cocaine Emporium on every corner now, presumably making marijuana a Schedule II drug won't change the Feds' stance on dispensaries too much. A non-renewable prescription for marijuana from a real doctor taken care of at a real pharmacy doesn't leave much room for medicinal marijuana as currently practiced.
EDIT II: The TL;DR is that unless you're an actual sick person with a condition that marijuana actually alleviates, changing it from Schedule I to II isn't going to affect you. That's not to say this isn't a good thing, it is, but don't assume it's going to affect people other than people with glaucoma or chronic pain, and they'll probably be getting cannabis pills in bright orange bottles like all their other medications.