For example in DropDownList reflection is used for binding for TextField and ValueField.
As an additional option, I'd instead to be able to do DropDownList<FooBarModel> and then FooBarModel implements a Telerik interface IDropDownListItem (for example but use your naming conventions)
I agree you shouldn't remove the option of using TextField / ValueField but I'd like to see it as an option.
Doing the same thing in something like DataGrid I agree would be a ton more work and we'd likely require using source generation.
It seems that Microsoft / the industry is consistently recommending to phase out the use of reflection and have invested a bunch in making source generation much less of a pain and developer friendly.