I don't think you can really compare the Amiga to the C64 - The Amiga homebrew scene should be compared to the Atari ST / Megadrive and SNES - against which I think it looks quite healthy.
The C64 scene should be compared against the spectrum which is equally good and the other 8 bit machines - BBC Micro - Amstrad which I think are less active.
The Amiga scene is quite healthy when compared to its 16 bit counterparts but to produce a good game takes a long time - to design - programme - produce graphics and new music for a game will probably take two years to do - Solid Gold - released in 2014 originally started development two years earlier.
There are many projects which get started but stall due to either a lack of programming skill , poor graphic skills or poor music creation skills - the solution is then to team up with a programmer / artist and musician - but then projects stall as it is difficult to keep 3 people motivated to complete a project for fun.
Even producing a game using game design tools such as Reality / Backbone will take 12 months to produce new graphics / music and produce something large like Tales of Gorluth.
Having interviewed around 40 programmers who were active in the Amiga homebrew scene back in the 1990s - most of them have moved on to mobile phone games or small commercial projects for other newer machines - or left programming.
For the Amiga scene to have a surge in games - two things would need to happen - firstly an easy to use game creator would need to be released to enable more people to become involved in game making on the amiga but there is little incentive for someone to create this - secondly the demand for the machine would need to increase to make it worthwhile to release a game on the machine - Realistically, I think the most potential sales you could hope for would be 100 at a price of under £5 and if you looked at £10 or £20 under 50 units.
If you are interested in seeing how long it takes to develop a simple game on the Amiga- you can follow the development of my Amiga Dizzy game on the following facebook page -
The game was started November 2014 - and I estimated it would take to July 2015 to finish which I hope to meet the deadline but work / family and other commitments can hinder progress.
Overall, the Amiga will never have lots and lots of games released each month or year - but you should normally get at least one good homebrew title released each year - I would argue that 2013 - 2014 were good years for the Amiga (Incredible Adventures of Moebius Goatlizard - Solid Gold - Solomon's Key -International Karate - Maxwell Mouse And The Missing Game Mystery and lets not forget Putty Squad finally got released on the Amiga as a freeware title.