Can boiling a soup too low result in less flavor?
I'd say that recipe really is going to depend on how much flavour is in your ingredients.

Nothing really has much time to 'cook' so the end result is going to be very 'summery' ie not far off 'just heated'.

You can't sweat down onions &amp; garlic in 6 minutes, but what you can do is just knock the raw edge off them.
Everything else gets about the same treatment, &amp; should come out almost al dente &amp; tasting really fresh.

The massive hit of basil &amp; parsley at the end ought to make it zing off the plate!

If it doesn't… then I'd look at your ingredient supplier.  

Supermarkets are great at selling you things that look fantastic, perfect in every way - except they can really lack flavour.
One of my pet hates is supermarket parsley [&amp; coriander/cilantro] It can often be nothing more than 'green', with very low flavour. Supermarket tomatoes, eggplant &amp; zucchini can be very similar.