I can just hear my grand-dad's voice now...
"Just because you can do it with that tool, doesn't mean you should do it with that tool..."
Using a T15 to do this job is like hiring a stripper to rotate your tires. Sure, it's sexy, and your friends will all be jealous. And she could technically get the job done. So, for that, it's probably worth it for some. I'd rather just use my regular mechanic, though. I know he'll do a better job, and for less money.
I'm sure the T15 can handle drilling those holes. But the long and short of it is that some tasks, like drilling big holes through thick, dense wood, require a lot of force, and the juice to do those tasks has to come from somewhere. Batteries do get tired. AND they get hot enough that you can't charge them right away. Maybe not on the first hole, or the tenth. But it happens.
Corded drills are made for this kind of work. There's no battery to die, and there's no need for the mfr to use a motor that's built for economical use of battery power.
It's jobs like these that will actually remind you of just how powerful corded drills really are, and what they're really good for. No beeping, not hot batteries, no indicators that the battery is too hot to safely charge right now... just go, go, go.
Is the T15 up for it? Sure. Is it the optimal tool? No, not really. Come on... you know you have a corded drill kicking around somewhere. No, it's not sexy. But not every job is sexy.