I can quickly spawn for example 4 identical Hab modules and attach them to core of station without exiting orbiter which would be impossible with sc3...
Not being argumentative here, just informative, but this is not impossible with Spacecraft3. Cumbersome or more time consuming, absolutely, but not impossible. Just takes a little more 'prep work.'
Step 1: Copy /Config/Spacecraft/Spacecraft3.cfg to /Config/Vessels.
Step 2: However many copies of the vessel (your hab module, for example) you will need for your scenario, make that many additional copies of the .ini file in /Config/Spacecraft, renaming to what you will name the module in Scenario Editor.
Step 3,4,5: Launch Orbiter, Start your scenario, and open Scenario Editor.
Step 6: Click New
Step 7: Select spacecraft3, Give your vessel one of the names you chose for your ini file. Click Create>>
Step 8: Lather, rinse, repeat
You can then quickly spawn, for example, 4 hab modules (or however many you want/made copies of the ini for) and attach them to the core of the station without exiting Orbiter