hmm, well, if we use add-ons then we might be shoe-horning users into feeling obligated to get those packages... So, if you have no other option then yeah but in be sure to list the requirements. However, if we can get these up to speed using stock (or at the very least free assets/actions/scripts) then I think that could help.
That said, if that would be too far outside of the scope of the project you're working on, by all means don't feel obligated...
To be honest, this whole thread I think is something that will be built up over time and I'm sure there are many ways to achieve all these effects... and I would also like to encourage anyone that's reading this that if you have any options functionality and are willing to share how you did it, by all means... there are more ways than one to skin a cat, after-all.