Looks like a good deal, with the obvious caveat that I’ll probably never find time to play it, so I’d actually be getting nothing for 15 USD.
But is it one of those “deals” missing an important expansion? A cheap intro to get you to sink more money in the hope of a game that feels more complete?
Or, on the other hand, is the base game for 1 USD the better deal? Complete in itself, without bloat?
It would not surprise me if this is a move to see how they push more copies of Stellaris sold before getting the new one out, like they did with Crusader Kings.
I was not aware of a “Stellaris 2”, thanks for pointing that out.
For CK2 they made the base game free and discounted heavily on the expansions. I only took advantage of some of the expansions, but for a couple of friends it was great to have a go at the precursor of CK3 (which I haven’t had the time to play yet).
As you say, those are rabbit hole games, before you know it you can put hours on end in them, and only experience part of the features.
I got CK2 free at some point, never got into it.
I got it back in… 2013?
Played it more after a few changes they did with expansion like the Pagan Gods one or Council. Played it in bursts, you could say. It is a tricky game to learn, but after you get the gist of it, you can have a lot of fun with it dicking about changing history.
There’s no Stellaris sequel currently announced, although I’m sure they’ll do one someday. It doesn’t include the most recent couple of DLC, but that’s not surprising. Doesn’t make any major omissions otherwise as far as I can tell. It’s a better deal than what I paid for all this, that’s for sure. And no, I haven’t played it yet. 
Years ago I decided not to play 4X games anymore.
I really enjoy them but they suck me in for hours and leave me very unsatisfied afterwards (the end game sucks, just should stop before that). Like junk food.
And I don’t have enough time to play them, so many other great games out there which want to be played 
A Stellaris boardgame has just gone up on Kickstarter, so I suspect that the bundle is to help generate interest for that.