Hii.......Tell me one thing suppose i have websites with page rank 5 lots of keyword are visible in SERP but "When Google bot crawled your site, it found some issues with your content. These issues won't prevent your site from appearing in Google search results, but addressing them may help your site's user experience and performance." if had changed titles and description in every web pages as per webmaster sugestion then what will happen........will my keyword ranking down or not...........
Most likely no, they would not go down. Most likely correctinh the problem would not increase your ranking either, at least not in a big way or anytime soon. It would be as G says, helpful to your user experience. You should do it. But, don't load titles and descriptions with keywords. Titles an descriptions should include your keywords, but should accurately reflect the content of the page. Repeating keywords obsessively could cause a problem. Keeping it neat, clean and to the point will eliminate duplicate page errors and in the long run, help very slightly. (there is lots of info out there on 'how to write titles and descriptions')
It will make your user experience good and title of webpage is key of seo, remember three things which matter much in SEO 1: Title of the page 2: keyword in URL 3: keyword in Header Tag Follow Google Search engine optimization guideline to be safe from unexpected result.