webform is old and we just drop it,but aspx engine is very important.
1.The simple design the best design for template engine,aspx engine just use <%%> and <%=%>.
2.What You See Is What You Get is more important for template engine.
3.Code separation is the kernel for template engine.Razor allow csharp programer to modify the template is not good.
why?for example.I'm a Csharp programer,and I don't want to write template so I just tell the html5 programer to write it.
Then,I have to select aspx engine.because he only know about html5,he can easier to master it.
4.Expandability is very important,for example.I can add some <foreach></foreach><if></if><switch></switch> custom tag by my self.
and it's clear for html5 programer.
5.The Price.I can employ two person,html5 programer and csharp programer,also I can employ one person with html5 and csharp.
almost the same salary,but the diferent work effectivity.two person can work better and faster than one person.
So,Pls add aspx engine for asp.net5,it's the webform's advantage,and we need to keep it.（aspx and ascx）