If I create a MIDI track and after that I load a VSTi the MIDI track will be automatically directed to this VSTi! Yes and isn't that what you'd expect the software to do?. It can only assume that if those two actions take place that this is what you where trying to do. Insert a midi track and then insert a synth to output sound for that track while you record. For the life of me a cannot think of a situation where I would insert a new midi track, then insert a synth and not want the midi track to be assigned to that synth.
Mostly I work the other way around and I set up a few synth in the rack first, then I'll start adding midi tracks.
It's just a workflow enhancement. 99% of the times it is what we want. I don't think the older versions did this.
It takes 4-5 seconds to change the output of a midi track to the synth you want or even send the track out a midi port to an outboard hardware synth.