Ok.. nonsense beside.

The figures i got from IPDB and whats listed as licenced etc or obviously TV themed like Bugs Bunny etc show that a licenced theme overall will outsell a non licenced by around 10% going on number of titles in total and overall sales.
Obviously, TAF which outsold everything and TZ carried this percentage with over 20,000 and 15000 sales respectively.
But it should be noted that games like Fish Tales sold over 13000.....Getaway, again over 13000...even World Cup Soccer saw over 8700 sales... a theme that you wouldnt expect to do particularly well and yet it outsold many licenecd titles including CFTBL.
Looking at numbers alone you can see why a manufacturer would favour a licenced theme.. any accountant would push you in that direction looking at a table of figures, but its not the full story.
TAF is a great game to play as was TZ when it came out... magnets, powerball etc.... these 2 games had a whole heap of features that you just didnt see in one package... they blew everything else away at the time.
2 titles that did extremely well.. we have great games with cool themes.. its a sure fire winner.

Then we have licenced games that just bombed...Barbwire 1000... Freddy 2800 ( good theme though?) Phantom Of The Opera 2750... low sales for what youd expect of some good themes especially Freddy and Phantom.

So maybe a theme will carry a title better, but its still down to game play... couple that with the fact that we have ONLY seen licenced games for 15+ years and its a formula that has maybe run its course?
SEGA did nothing but licenced themes.. piss poor sales though generally with what numbers we have.
Licenced themes really took off in the 90's but some games sold extremely well before then in the mid to late 80's.. and this was during an industry slump due to arcade machines.

Maybe the themed machine was a novelty at the time that took pinball a step sideways... seems that we need another step sideways as the constant churn out is getting stale?