Right, the expense of converting to FX lenses is a big issue, which certainly should be given consideration. But still, in DX mode, the DX lenses can still do what they always did until that conversion. Nikon even provides Auto DX/FX switching for them. Except DX cropping on FX will be about 40% pixels and 66% resolution. Still generally enough for most casual purposes.
I found the opposite to be my problem, in regard to using FX lenses cropped in DX mode. A 12-24mm or 16-85mm DX lens is nice wide angle, and still does all it ever did on a cropped sensor. But now days, on a trip like a cruise (everything is just snapshots anyway, and excursion baggage is an issue), I only carry one 24-120mm lens with a FX body. I wish it were f/2.8, but it always seems extremely decent on FX. But if a notion to try to save memory card space with DX, then that 24mm on DX mode is not much, only very mild wide angle. That loss of wide angle is a very major loss. I found it necessary to set wide angle mode by switching back to FX mode.
Carrying another wide DX lens would have advantage then, but just carrying another memory card is more feasible.