Since cartos are specifically an add-on, going right to the 2 ohm makes a lot of
sense to me. They give a decent starting point. If the person then wants to branch out, going to drip tips, LR atties, CE2,... they can, but will at least have a decent initial set of stuff to work from.
There's also the potential for an oddball atty in a kit. When I picked up my first Riva package I did a doubletake, surprised at how cruddy the
vaping was. Fortunately I had LR cartos, went right to them, no problem -- it turned out that the one atty, right in the Riva kit, was actually 3.4 ohms (fine for a VV, not so good for standard Riva battery); the other atty was 2.4 ohms (haven't used it since I like cartos).