The thing is, in beta, Soviet needed to build T3 to get T-34/85 and IS-2 or T4 for ISU-152, Ostheer needed T4 to get Tiger but dunno why Relic changed this. Noted, it was also the time when Shocks/Guards needed T1 , 120mm mortar needed T2 to call in.
I for one am glad that things aren't done in this manner, as it would be entirely too resticting for the soviets.
Why should I have to build a building that provides me the option to build a mortar to use a call in for a mortar? Why should I be restricted to having no real AT to build shocks? Why should I make a tech choice that provides me a T34 so I can call in a T34??
That sounds like a horrible system imo that would strongly discourage combining units with different strengths and weaknesses.
Also, regarding forced techs for callings in general, I don't see what the point is. Is it's entire purpose to delay call-ins? Why not just increase CPs if it is an issue?
I think what you will find is that people just build a building and use the call-ins anyways. Not unlike what I have done on occasion when I'm a half a CP away and have fuel to blow. I build the building to get me to 8cps for T34/85 and never use the building again.