We are aware of tripsteem, in fact we had several posts submitted to TravelFeed through tripsteem. It is always great to see when people are working on tools for the Steem travel community.
Their website seems offline now, but we usually see a post submitted through them to TravelFeed every few days. You would have to ask them what is happening to their project, there seem to have been no major developments since last year. Tripsteem doesn't seem to have any community outside Korea, while we have been building TravelFeed as Steem's largest travellers' community for the past 1.5 years. Dapps that "noone uses" are usually the ones who have failed to build a community.
The numbers on stateofthedapps are based on steemapps.com, which currently does not count TravelFeed users at all. We have reached out to @therealwolf who develops/manages Steemapps more than once to fix this, but never heard back, not great for a consensus witness. Hopefully there will be a Steem foundation eventually to manage projects like Steemapps.