Yes, the HTML is cleaned to remove <input> <script> and other "dangerous" tags.  This is done because the HTML template can be provided by an Administrator. If it contained <input> or <script> tags (etc.) an Administrator could inject malicious code to gain elevated permissions (i.e. they could become a SuperUser).  I will consider reviewing the security model but I can't guarantee exactly when that will happen.

As a temporary workaround, if you are familiar with Visual Basic.Net or know someone who is, you can take a look at the source code and remove the line that performs the cleaning.  I believe (don't have the code with me, atm), it is in the Visualizers/HTML/Visualizer.ascx.vb file.

Andrew Nurse
DotNetNuke Core Team Member and Reports Module Project Lead
Microsoft Certified Professional Developer

I'd suggest looking at something like OpenWebStudio which is a free open-source development tool for DNN.

Here you can work with form elements and I've added a sample configuration for this here in their forums.

Hope it helps.