I'll go first. Their role makes the work of government agencies even more complex. It becomes very hard to know who is doing what in this new environment where anyone can call themselves a hacker to answer the call for help, with very good intentions, I don't deny that.
The risk is that some of the hackers may not necessarily know all the ins and outs of the systems they are attacking. As a result, they may launch attacks against critical infrastructure in Russia to the detriment of Russian civilians, who don't necessarily have anything to do with the attack on Ukraine. Those cyber-attacks have the potential to spill over into other countries, beyond Russia's borders, and be hard to control.
I think the situation needs to be approached with a great deal of care. It's important to not get excited and to think about all the uncontrolled and unforeseen implications of cyber-attacks mounted by isolated groups.