If you are not indexing tags, then no problems. But even then i would recommend keepnig 2-3. They are not meta keywords. Meta keywords were the ones which were filled in on an article. When meta keywords became obsolte, people started abusing tags. But now even tags are being punished by google as duplicate content if there is a lot of content on multiple tags. So in essence, dont put 7-8 tags per post. Put 2-3. In my site, i have indexed tags and i have 1 single tag per post. Not even 2.