Measuring isn't copying in my book. Looking at others work and picking out what you like isn't either, that's been around since cave painting. Besides, if Jerry measures a Hetzer and it's the same as a Tamiya, that means they're both right.

I frequently buy competitors items to see what they're up to. If I find a new interesting method they've used in their molding, by all means I'll incorporate it into my next sculpt, just as I expect others would do to mine. But I won't physically copy anything, I'm copying ideas. That's progress, because everyone is always trying to improve.

In terms of modeling companies and going out of business, injection molds are capital and usually are the first thing liquidated. Accurate Miniatures had an amazing line of 1/48 AC. They went belly up years back, but those molds are still in circulation (Italeri I think). But that point really isn't realistic. By the time you mold and copy, you've far out spent the price of a pile of kits. Few people will go through the expense to copy an entire kit, unless they're planning on selling.

In terms of detail parts, if you copy, bad. If you use one to make an entirely new piece, by measuring, replacing, embellishing, whatever, that's okay. Look at all the aftermarket products for AC. The one I've always loved is weighted tires. They are usually just the kit rim, recast with a tire that has a bulge to simulate the weight of the plane. Excellent idea, new product, doesn't hurt sales. Eventually the model company starts molding weighted tires themselves...progress.

Except in the case of DML with the US halftracks. They released them weighted front tires. Only problem was the HTs had solid front tires, hence no bulge.