They're ok to offer in small amounts as part of a variety, but I wouldn't rely solely on them. Try to rotate what you offer to provide the healthiest diet. Other good options include silk worms, black soldier fly larvae(calci/repti/phoenix worms), hornworms for adult dragons (they grow to be too large for young dragons), roaches, crickets, morio/super worms. There are other good bug options available too.
Yeah... it's a debated topic. There is some concern that the hard shells can cause impaction in young dragons. I haven't seen that be an issue as long as lighting and environment and overall health are good. Overfeeding them can be a factor in that as well. Generally they are pretty good at chewing if they aren't feeding too quickly and that breaks them down enough. Impaction risk decreases quite a bit as they get older (again, as long as their health is good and environment is correct etc). I don't really see an issue with offering them as part of a diet as long as it's not too much and not the only offering. That's just my opinion though and others may disagree, and that's OK.