It's already as is a good enhancement, as all content in meta tags will be actually found in the page.
As well, the title should (I mean, we cannot do much about bad content) contain the most important keywords of the post and be descriptive. With good content quality, this can give us some pretty good and short meta tags which is a good thing.
For example, the idea to grab some part of the first post to build up a description is not this good I think, because a lot of interesting post starts with un-interesting content, such as "hello, so yes you are right, this bla and bla", before the interesting :"now let me elaborate more on this precisely".
Here, the keywords the most likely listed are the one being the most used in the forum being as well being inside the post content (all of it). So if you go through the
search table optimizing process and run a well organized forum with good content, you'll end up with very good keywords in the meta tags, as keywords should really be keywords anyway, thus used a lot in the forum.
Besides, if meta are not dead, it's not a reason to go for the absolute perfect meta for all pages, would be useless SEO wise I think.
The important matter here is dynamic, honesty (the content is related to them) and efficiency, few server load for dynamic meta everywhere.
Anyway, I'll update this and will add some more features, but it will not further what is really necessary and useful SEO wise.
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