I'll open myself up for correction on the matter, but it's been my experience that these days Asterisk is more useful as and often more commonly deployed as a feature server (hunt-groups, ring-groups, call trees etc), at least for a broad majority of use cases where SIP is even a part of the conversation. Personally I'd not recommend one try rolling their own Ast based phone system for production/enterprise unless you just really want to and have literally no other projects to deliver back to the org.

Otherwise, what you're doing is perfectly fine and well enough: connect to your SIP trunk via credentials using a local client and you've more or less got a working, accessible phone number. Unless you truly have a need for Asterisk features, don't bother.

I happen to know first hand of a "voice company" that has a pretty sizeable footprint in the travel/hospitality industry making several million dollars a year and one of their products amounts to nothing more than configuring IVRs and charging through the nose to host them using what is (in my opinion alone) a thoroughly overly-complicated Asterisk infrastructure and similarly overly-complicated dial plans.