It's a bit ridiculous to imply Tokuyama gets better shinkansen service than Hamamatsu, because it has Nozomi service.

Looking at the schedule towards Tokyo for Monday, April 27th: Tokuyama has: 4 16 car Nozomi trains to Tokyo 19 8 car Kodoma/Sakura trains to Shin-Osaka 9 8 car Kodoma/Sakura to Okayama

Hamamatsu has: 31 16 car Kodoma to Tokyo 19 16 car Hikari to Tokyo

Keep in mind the fastest Kodoma seems to only take around 1 hr 40 mins to Tokyo, and the fastest Hikaru is only 1 hr 20 mins.

I'm sure it's nice getting a 1 seat ride to Tokyo from Tokuyama if you can get on one of the 4 Nozomis, and unfortunate you can't get a one seat ride past Shin-Osaka from Hanamatsu, but the service levels seem pretty proportionate to me.