We don't need optimal decisions, in fact politicians are also not experts at the decisions they make, even worse, they make decisions based on who paid them to make them. What we need is proper representation and distribution of power.
The idea of a republic is that one elects a wise leader who can take the time to understand the issues and surround themselves with knowledgeable experts that can help fill in the gaps — which isn't even remotely possible in a direct democracy, as not everyone can know an expert in every necessary field.
Now, that said, our country is obviously quite far from an ideal republic. But I think it's other things — gerrymandering, a lack of good participation by voters, and a FPTP voting system that forces a two-party system — which many people think would persist pretty much as-is in a popular vote system —, and forces voters to vote for someone other than who they want to vote for. (Some would also add money-in-government, i.e., rolling back Citizens United; I'm still on the fence there, myself, as it would also prevent coordinated efforts by citizens.)
I don't know how to fix that, but I'm very doubtful that abandoning representative democracy in favour of direct votes on all governmental decisions would be a positive step. It seems likely to just hand even more power to whichever charismatic populists and fashionable "influencers" can persuade people to vote blindly for whatever they promote.