The DIRECT launcher system is touted as being able to lift things which we need Shuttles to lug up to space now, in chunks up to just shy of 100 metric tonnes.
Because the one lifter would replace two, it immediately saves 16 billion USD in development costs (35 billion eventually, they say). Due to using Shuttle parts, much more development & learning is also bypassed.
The little, baby one lofts 70 tonnes (or an Orion CEV module plus 48 tonnes) so could lug large Hubble parts up to service said ’scope, and could also lug up chunks of ISS to Fred, in lieu of pieces scratched by the approaching Shuttle end-of-life (Centrifuge Accommodations Module, Habitation Module, Propulsion Module, Science Power Platform, etc).
I think its most appealing aspect is that — to put it politely — it’s not beautiful. It looks like a Shuttle tank & boosters with a few trinkets strapped onto the top. In other words, it looks built to task, rather than built to impress.