OK, I appreciate that the main intention of scavenging is to sink gold - and, in that intent, it does a reasonable job. BUT, it could sink a LOT more if changes were made ...
I've just spent 15 million in the Mystic Cave, looking for "Barathor, the seer of Fire". At 45,000 per attempt, I actually SAW him only 17 times - so, a spend of 765,000 gold. The rest of that was wasted on random rubbish that I had absolutely no interest in.
Now, some folk could see that critter with a higher frequency and some could see it with a lower frequency, but the fact remains that if you see your "target" creature (I mean specific LE creatures in the caves btw) more than 5-10% of each attempt, then you're doing really well. If you get drops, then you're doing even better. I got one drop from Barathor - thankfully perfect - but 1, nevertheless.
The fact that I dont even SEE my target creature for approx 95% of my attempts dissuades me from spending copious amounts of gold ..
IF the caves were updated - by the addition of a third cave for "specials" where you ONLY saw those specials (with a lowered drop rate - and maybe even an increased cost) - then I'm sure folk would be willing to spend / sink more gold. Reducing a double-whammy chance of success to a single chance of success (chance of actually finding and then getting a drop as opposed to just the chance of getting a drop) can be nothing but a step in the right direction and thus a win / win.
After all - more gold sunk and players happier because they actually SEE the creature they're after - what can be wrong with that ?