In my case the reasons for not adopting Silverlight yet are as follows:
1) I'm not at all confident that I can guarantee that the client users of my system will have Silverlight and indeed in many instances owing to corporate governances they may not be allowed to install it. Obviously that will change over time.
2) I don't have any clients in this camp but anyone without a Windows PC will have a bad time using Silverlight - for example the Linux implementation doesn't fully work - correct me if I'm wrong on that as I haven't personally tried it.
3) You are right about the learning curve being present but that doesn't bother me too much. That said, one tremendous thing that you could develop is some form of converter to translate the setup of an ASPX page to a silvelight page. That would certainly speed up some of the re-working of a system.
4) This is MS's fault in that when I looked into it you can't get a VS 2010 Pro Upgrade from VS 2008 Pro. They seem to be only doing upgrades with the MSDN subscription which to me isn't worthwhile for the huge cost (I certainly wouldn't get anything from it other than new software versions and a free Windows 7 licence). If someone knows different please correct me. The reason for this point as I'm sure you realised is 2008's useless support of silverlight controls - would be as easy to do it all in notepad.
Having said all of that I do want to develop a Silverlight version of our system towards the Autumn so that the in house users can use it. I fully appreciate the massive benefits that SL will bring in terms of shared code base with a WPF app etc. To say nothing of the fact that style wise it makes ASP.Net pages look like something from the dark ages.
For any charting solution I think that functionally needs to be something like Chart Director (although the appearance of that is looking a little dated now). For me Gauges are very important too as they provide a highly visual quick glance at a single or set of figures that otherwise would look bland and boring.
A little off-subject but from a personal perspective I think that the following are the big areas that Telerik should be focussing on with respect to development on existing stuff.
1) Appearance of controls. Let’s have some new controls that have a great modern look BUT can be shaded according to the users colour set. Ie. For example say that the Theme is the Windows 7 theme but I want a green colour wash over it. In an ideal world setting Theme.BaseColour="00FF00" or something to that effect would be great. Yeah somewhat "Pie in the sky" but it would make theming a lot easier - choose your style, then your colour.
2) Make sure that all controls share the same themesets - ie, charts, report viewer and aspx stuff all can draw from the same pool of themes. For example, why doesn't the report viewer in aspx have the same set of themes as the combobox or grid?
3) Improve the Charts and Gauges (implement in ASP.NET). The Telerik controls provide great admin functionality but lets looks at the data presentation more.
4) Enhance the Editor controls so that they can relate to each other with a FormView killer. The formview is in theory great especially as it combines View, Insert and Update into one ASPX file but in practice using it is a pain in the neck. I want to be able to say on a combo box that these are it's children and when it's updated that the children load their parented values, have built in validation on the combos and other fields etc. I think that providing the editor controls is one thing but to really use them efficiently there is a big gap between where they are at and where they need to go. I feel that there is nothing on the market at all that allows for really fast rapid development of quality forms and think that this would be a huge differentiator between yourselves and other control providers. This form builder idea would be useful across all platforms. Frankly I’d be willing to pay extra for something that took my development time down in this area.
5) Make the controls more friendly to different sizes – this is with respect to icons. I tried a while back to get some 32px icons into the RadMenu but just gave up after hitting so many issues with the stylebuilder.
6) Add a button control that will do the normal FormDecorator button appearance but that can include icons alongside the text – this would be a great way for all of us to quickly boost the appearance of our systems. Don’t do it as a FormDecorator but as RadButton.
7) Lastly a decent Panel control would be great. I use the RoundPanel from Devexpress at the moment but that’s annoying having to mix controls from different providers – especially on the theme front.
Hope all that helps!