Honestly, I do understand that blink wanted to play it safe in order to get themselves relevant in the mainstream again. But I don't think it was necessary. You can be experimental and be mainstream. The single doesn't have to be something like BTD. Just look at I Miss You. Blink themselves didn't expect that to be popular but it was. Green Day weren't relevant in the early 2000s until they experimented with the American Idiot album.
All blink needed was a hit or two. Doesn't matter if the song is experimental or not, it can still be a hit. As for Matt Skiba coming in, I doubt casual fans would even know the difference between Matt Skiba and Tom. Really, I think of it as a no win situation when it comes to the hardcore blink fans. It was either two options for blink. One was to have the gothic punk rock sound that Matt would bring to blink, alongside his new wave elements and Mark's +44 vibes. Two was to try go the more mainstream sounding route, which is what they did.
Doesn't matter which option they'd choose, the hardcore fans would be split. Some blink fans just don't want that Alkaline Trio gothic punk sound with blink, but there's also some who'd love it, me being one of them. So they went the more poppy route, but again, some blink fans just don't wanna hear that anymore, especially after hearing BCR, +44 and the 2003 album. Me personally, I don't actually mind that they went the more poppy route. It was the fact they went so overboard with it. There was just no need for every damn song to have a fucking woah or nana or whatever crap it was. One or two songs is enough. Gang vocals also do not work in a blink song either IMO. They could've done pop punk in a more blink way, not a crappy ATL way. That's just my personal opnion though. Everything they did just wasn't necessary at all IMO. Yeah, it worked, but it could've worked other ways too.