Why these page exluded as Blocked by robots.txt ?
This is your site, you are supposed to know :) ... teasing apart, this is certainly because you are using a CMS, which added this entry to your robots.txt.
Is good for my site?
Again, it's up to you to see, but "usually", there is no point of letting search engines to crawl your search page. These pages will rarely be ranked, and if your site has a good navigation structure, search engine will already find all your pages naturally.
Also, since you can have an unlimited number of search pages, it can unnecessarily exhaust your crawl budget.
So in other words, I would let things as they are.
If you remove this line, and put a noindex, then it means that crawlers will still consume resources to access the /search page for nothing, since they'll be told not to index it.
edit: I don't know if my explanation are clear, because I am drunk right now. You know how alcohol can help you forget ...