First, it won't be a $300 meal.
Second, the Fantasmic Package is a free addon to a TS meal IF you wanted to do a meal at one of the participating restaurants anyhow.
Third, no, it's not worth the package (anymore, it used to be back when they had the Golf Cart Service and other benefits). And no, it's not worth FP+.
However, you will be forced to wade the preshow crowd if you don't use either of these.
I literally have shown up to Fantasmic with my kiddo 15 minutes before start time (avoiding the traffic jam and crowds) and still had pretty darned great seats due to the simple fact I ate lunch at Brown Derby.
So, is it NECESSARY? No. Is it nice? It can be.