Panel lines why use them ?

True. Except on larger scale models such as 1/32 & 1/24, they are pretty much out of scale. But they do add visual interest to an otherwise plain surface. I think the current trend of recessed lines and rivets is often overdone. Many vintage aircraft had overlapping skin panels and raised rivets, yet that is seldom replicated accurately in any scale. Nearly 50 years ago, Revell was repilcating flush rivets on some of their 1/32 kits with embossed circles around the rivet head, rather than as simple divets. This produced a far more accurate looking flush rivet. If it could be done with the mold technology available then, why not now?