We are definitely spoiled in terms of sheer numbers. Here are the number of MPs released by both Takara and Hasbro since the beginning.

2003/4 = 3
2005 = 1
2006 = 3
2007 = 3
2008 = 1
2009 = 5
2010 = 6
2011 = 5
2012 = 7
2013 = 11
2014 = 14
2015 = 14
2016 = 13
2017 = 15
2018 = 15
2019 = 18

So looking at 2003/4 to 2019 that's 16 years worth of MPs. If we look at the first half of this period, we can see that the average number of MPs released per year was 3.38. The average number of MPs released in the second half is 13.38! So we can see that the average number of MPs released per year is nearly quadruple (x3.95) the average annual release from the first half.

That's a lot. So yeah, the early years of MPs may seem to have fewer QC issues but that's because there were fewer MPs being produced. And when I say that 2003/4 had 3 MPs, I mean that we had:
* MP1 Convoy (Takara)
* 20th Anniversary Optimus Prime (Hasbro)
* Lucky Draw MP1 Convoy (Takara)
Most collectors would've only gotten just one of these, so in reality most of us were probably collecting maybe 1 or 2 MPs per year during the early years. One reason why the number of MP QC reports may have risen may simply be due to there being more MPs existing these days. Even if you're an MP completist, if you're only collecting 3 MPs a year in the beginning, there's going to be fewer chances of encountering a dud MP. When you're collecting 13 MPs a year, then suddenly the odds of encountering a faulty toy has greatly increased. If you collected 18 MPs released in 2019 then that's 3.6 times more than the measly 5 MPs that you collected 10 years prior. The chances of you encountering a faulty MP is higher.

What I'm curious to know is how many dud MPs people have encountered VS the number of MPs they collected in each of those years. For me it would look like this:
[MP Year] = [No. w/ QC probs] / [No. of MPs acquired]
2003/4 = 1/1 <---this means 1 out of 1 MPs that I collected had a QC issue. My MP1 came missing a panel.
2005 = 0/0 <---I never got MP2 Ultra Magnus and thus never had one with a QC issue.
2006 = 0/1 <---the only MP I got this year was MP3 and I had no QC issues with it.
2007 = 1/3 <---I got all 3 MPs released in this year and one of the tiny panel tabs on my MP5 broke during first transformation.
2008 = 0/1
2009 = 1/1
2010 = 1/1
2011 = 0/2
2012 = 0/4
2013 = 1/7 <---my MP15 Rumble came w/ 2 of the same side piledriver arm.
2014 = 0/4
2015 = 0/7
2016 = 0/9
2017 = 0/5 (unless you count some minor paint chipping on MP36)
2018 = 0/2
2019 = 0/2
↑So that's how it works. Feel free to copy, paste and edit this for your own MP collection. But yeah, the only QC issues I've really had was with MP1 (missing panel), MP15 (missing 1 piledriver arm) and MP5 (snapped panel tab).

Also note that I've counted the MPs the same way that tfwiki has, which is counting releases, not individual figures per se. So I've counted MP15 Rumble & Jaguar as one release, and the Hasbro release of MP Soundwave (with a whole bunch of cassettes) also counts as one release. It's counting releases, not figures... just for the purposes of this discussion - don't get your panties in a knot. And of course, if there are any years where you didn't get any MPs, then just submit 0/0 (as I did for 2005).