Reason software can be used either as a complete virtual music studio, or as a collection of virtual instruments to be played live or used with other sequencing software.
The fact that you can't record audio or operate VST's makes it very hard for the moderately skilled and above to take Reason to the next level. Welcoming third party software while allowing users to utilize the best aspects of Reason will ultimately take the program to the next level. Rewiring to Ableton can only satisfy for so long.