I like that idea voting for ideas instead of people.
You see this a lot in local elections where often there are specific ideas on the ballot for local people to vote on. I want to vote for "more public transit options" but it's not as if I'm voting for specific train lines or bus routes.
That's before you get into the issue of who is coming up with the ideas to go on the ballot, how they word them, and how carefully they consider them. It's easy to make a lot of things sound good on the snippet you'll read on a ballot, but not prevent bad side effects that you wouldn't think about.
Without the limitations of current voting system, there will not be useless votes like "more public transit options". Instead of that when you are stuck in traffic jam you'll create a proposal for a specific line, other people stuck in the same jam would support it, then your city will hold a competition with different companies proposing different solutions, then will be a vote to pick one of them.
While it sounds good in theory, you're leaving the country to the same sort of crazy on NextDoor who has nothing better to do but peer out their blinds during the day to report the suspicious activity of someone walking their dog.
Year 1: vote on idea
Year 2: vote on ratification of idea as well as the committee members to design the implementation
Year 3: we vote on which of the 3 - 5 design proposals the committee designed to implement as well as the executive team to implement the plan
The issue is the same as letting someone spend his own money, he may end up spending all of it on something stupid (like alcohol), and some people indeed do that, but most people end up spending rationally.