Please consider the fact that you don’t know all of the reasoning behind the decision. VATSIM is moving away from the FAA-style flight plan and over to ICAO-style flight plans, not just in the web form, but also at the server and network protocol level. It makes perfect sense to have all flight plans flow through the web form, so that all pilot clients don’t have to update their forms and network protocol to ICAO style and maintain them as the flight plan system evolves over time.
You say this is the “worst idea ever” and I say that your excuse of not having a browser is the “worst excuse ever”. If you have access to vPilot, you can have access to a web browser. Also, you can do what most full cockpit users do, and file their flight plan from outside the cockpit before entering. After all, most real airliner pilots don’t file their flight plans from the flight deck. And most non-airliner pilots that file from the cockpit will do so using a tablet or phone, which you can do as well.
I believe the tech team is indeed working on the ability to load/save plans and have the form remember your last-used values. These were the final improvements I was waiting for before removing the flight plan form from vPilot.