You will be told that millions of players playing the game are more likely than a small team to identify bugs.
This is true of any game. AAA games like Fallout 4, The Witcher 3, etc. all had bugs and glitches after release. Batman: Arkham Knight was (is?) virtually unplayable on PC. It happens. No game - no non-trivial piece of software - is completely free of bugs. Ever.
Despite being "indie" and "small", Terraria is enormously complex as a piece of software. No two people play it the same way, and every world is different. Combine that with thousands of different mobile devices (and the OS implementation on each is slightly different), and you have the potential for a lot of bugs and glitches.
There is no doubt that the QA process failed here - there should not have been this many bugs and crashes. It seems clear that the QA people had little to no experience
playing Terraria as people tend to play it; going forward we hope to have a team of 'Terraria experts' to do the gameplay testing - people who will recognize when a weapon isn't dealing the proper damage or looks wrong. We could not get that team in place in time for this update, unfortunately.
Playing and bug searching aren't the same thing.
I couldn't agree more with this statement. Yet finding people willing (and able) to do bug searching, along with the documenting and recreating required to find a resolution, is quite difficult as well. The vast majority of people who say they'd be willing to 'test' a game are far more interested in early access to play than in actually doing testing.
We continually try to change the process to make it better. This has been an eye-opening experience for everyone involved, I think.
[Disclaimer: I do not work for 505Games/Re-Logic/Codeglue. I was not involved in the development/testing of any version of the game, though I have worked as a software developer/engineer in the past. These are my opinions and observations.]