Nice work Starway!
DCS is a hobby for me, and we all know that we always spend crazy amounts of money in our hobbies that cant be justified with common sense, so if someone makes our hobby better and improves our experience its correct that we compensate him for it.
Personally 15$ to improve my visual experience throughout the game is worth it. If Starway gets compensation for his work, he might also be inclined to produce more and better stuff in the future, so we are actually investing for many future mods, if you want a proof, look ar Blatic Dragon, he is the perfect example of making the experience improve.:)