In the past new engine versions have not contributed "killer features".
From Gamestudio's own Wiki page:
1997 ACKNEX-3 released [3]
1999 A4 released (Windows Based Quake-like Engine)
2000 A5 released (Terrain Engine)
2003 A6 released (Physics and Shaders)
2007 A7 released (new ABT renderer and Lite-C)
2010 A8 released (Enet Network Library, Nvidia PhysX, PSSM)
In some cases, a total engine rewrite was a part of the version release. That's pretty major.
Also, concerning the free updates to owners, the Wiki page says this:
Free updates are normally available once every 4 to 8 weeks.
It has been 5 months already with no new beta, let alone a free release to existing owners. And, yes, I do realize that there have been dry spells in the past.
