Q:

Is it ok to take suggestion on an opensource project idea? 

There're many opensource projects shut down because of less attention, less need, duplicate, and other reasons.  People might want to take an opinion of others if it is worthy to spend time on any new opensource project.  devRant's collabs is one of the example. 
Would it be fine to ask such questions to take an advice on opensource project ideas on opensource.stackexchange.com? 
Example questions

Should I create an opensource SVG editor in riot.js? 
Do we need another opensource HTTP router in node.js? 

Sometimes people may end up asking questions related to tech stack.  However, my question is only about idea not the tech stack. 

A:

The Stack Exchange platform in general and Open Source SE, in particular, is suited for questions with specific details and specific answers.  Answers may be long and there may be a discussion on the reasoning behind them, but ultimately, it should be possible for users to decide whether an answer is right (and potentially upvote) or wrong (and potentially downvote).  
Questions like those you've proposed are open-ended and essentially opinion-based.  There is no right or wrong answer here.  So to make a long story short - no, these sort of question are not a good fit for Open Source SE, and would probably be downvoted and closed as such.