Though there are many better ideas like semantic search, entity search, Q & A, deep search, etc. Startups could crack some market share from big players. Building better search engine is not the big problem for startups, but from business perspective, It's a marathon race - in terms of scale, investment, making the user switching from google etc. also Google have billions of $$, thousands of researchers working to improve the results, competing them is not easy, hence many stay away from search engine development.