I think the Carrack will pretty much like you say, weapons to defend itself, and it'll probably focus on drones along with its mapping suite. Drones are the new LTI in SC
It makes sense really, like the Reclaimer having them to shoot off and scan the area for items of salvageable interest, i think the Carrack could have something similar, with a different focus.
Likewise these add-on ships/rovers are... the new Drones
(keep up!) Every ship seems to be getting them, Constellation, Idris, Constellation variants got 2 new versions, the Reclaimer has one, 890 Jump just got one, dont be surprised if the Mustang gets one
Like you say, not really sure what its purpose would be as such,
but exploration isnt simply about discovering vast places nobody has been to before, but places people havent seen, a ship could fly straight past without knowing its secrets, and maybe the Carrack has the suites & drones to spot the small things, and you'd jump into a small vehicle and take a closer look.
The alpha stuff really sucks hard IMO, it annoys me and i only have a $45 LN, so hardly a $140 Freelancer or $275 Constellation. The 'package' stuff should have a value, the ships have their own values, well so should the packages. They should have them ranging from basic to high, virtual & physical. So if i want a $30 Aurora and a $50 physical package, i can. If i want to melt the Aurora and buy a Carrick, its my choice to do so. But no. Its one of the few things that really annoys me with a decision they've made. They could also do something to 'remove' the Alpha from the package, and apply it to the account. You sell it, you still need a package for AC etc. But you dont need to worry about losing it. If you want to gift an alpha package you can too, but obviously if its been transfered from the package to the account, gifting it doesnt incl the alpha, just like any package you'd buy today.