If you always camp with hookups at full service campground they would be of limited use.
If you like to camp without hookups then solar and more battery storage may well be worth while. Adding the inverter in this case would allow somewhat limited use of 120vac appliances if you desire to use such. Some do, some don't.
If you are new to trailers and camping, spending the $ is not an issue, and have no idea how you might end up using the trailer, it might be a good idea to add them now. You can have such added later, but it's cleaner and easier to have it done now.