Sounds like what Rob is suggesting is his survey feature could potentially be used as a way to create custom forms.
I think the core of what you've hit on is that we lost a little something in the transition from Classic ASP which is an interpreted scripting language to .NET which is a strongly typed compiled language. The scripting model has an advantage in that a designer can learn just enough and be able to develop forms. To me the designer is kind of being a junior programmer in this task and the barrier has gotten a little higher in .NET. I think in this case the designer is going to have to learn some new tricks. Its further complicated/made difficult by the fact that mojoPortal uses the pre-compiled code behind model of the ASP.NET Web Application where all the server side code is precompiled into the bin folders as dlls. There is another model with the ASP.NET Web Site Project which does allow deployment of source code which is then compiled as needed autmatically. This model is perhaps a little more conducive to a designer/junior developer being able to edit files right on the server without having to compile.
I have some ideas about trying to bridge this and make it possible to add pages with mojoportal that contain raw source code but I need to experiment with it to see if it works. I'll try to do that soon and report back.
The other thing you've hit upon is that only 1 form can be on a page in ASP.NET. This is not a mojoPortal specific limitation this is limitation of ASP.NET that not everyone thinks was a great design choice on the part of MS but is nevertheless the way it is, some call it a feature, others deride it as a design flaw.
So I think there are several possible strategies to adapt the workflow.
1. If we implement some kind of form wizard type feature in mojoPortal a la Rob's Survey feature
2. The untried idea (that I will try soon and report back on) that would at least make it easier to deploy pages with code written by the designer. Even if this works its going to take the designer learning some C#