For questions and answers, you can flag it for moderator attention, but I see no such feature on tags. The fact of the matter is 250 reputation is a lot less than 2500, and a lot of useless tags are going to float around on most sites, especially beta ones with less high reputation users. Adding an option to flag tags will let lower reputation users who browse tags do something when they see a bad tag other than just ignore it or post something on the sites meta, both of which are much worse options than just flagging a useless or bad tag.
Edit: as pointed out by the tinkeringbell in the comments, flagging tags might not be the best idea. Maybe instead add a queue where bad tags are, similar to the re-open queue for questions. The way I imagine this working is that one user with not enough reputation to get rid of a tag marks it for the queue, where users with enough reputation to get rid of tags can review the queue and delete tags that are a bad fit for the site. Also, to prevent trolls maybe scale the amount of people needed to delete a tag based on how often the tag is used.