Material design doesn't work for everything, it makes email/messaging and a file manager look identical. Show me a titanium backup alternative in material design that has identical features?
Show me how you could possibly get something like an email, messenger, or file explorer confused with each other. I can certainly tell you that I've never opened Messenger and confused it for Gmail. Or opened Solid Explorer and wondered where my converations were.
Updating to Material Design for a cohesive experience across apps is a desirable thing. What was your point, there? I'm guessing you enjoy using a Lollipop looking Gmail, a JB-KK messenger, and an ICS file explorer? Feels like a unified experience?
And naturally, you pick the one app whose UI has been updated once (and a paltry UI refresh that was), receives constant complaints about said UI, but still gets use due to the quality of the service rendered.
You're right, TiBu and Helium are not MD. But TiBu's interface isn't fantastic. It's downright atrocious. People deal with it because it can't be beat for what it does. This doesn't mean it's lack of MD is a valid counterargument. I can guarantee that if someone could match TiBu on features and bring a modern UI, everyone would flock to it. However, while their UI has never been caught-up, they have constantly updated to incorporate new features only available to newer OS's as well. Win some, lose some in their case.
I used appearance as an easy retort. If you want to take everything I say as an absolute and only at face value and use one-off counter-arguments like they're end-all-be-all, that's fine, I guess. You won't get anywhere.
Solid Explorer has shown that it's feasible to take a very feature-rich app and make MD work. The devs of TiBu honestly just need to hire a designer.