In the nearly sixty years I've been in the business of repairing, restoring, buying and selling guitars and other fretted instruments I've seen more than a few changes though some things have not changed at all. In steel-string acoustic guitar design, while there have been some really interesting sideways moves by makers like Taylor, the basic basics that Martin had worked out by the late 1850s remain, ineluctable. Some manufacturing processes have been improved upon though, notably in the use of CNC machinery taken from the automobile industry, to make various basic parts more uniformly and more easily. This effort led, once again, by Taylor and winningly so. For electric guitars, what is there to improve upon or change other than the occasional addition of active circuitry? The basics, around since the 1930s and no more complicated than some toaster coils and a few magnets, is still the same, other than the brilliant colors and finishes brought on by PRS some years ago and still unmatchable. Changes in the music, well I'll leave that to you as musical discoveries and trends and tastes have been changing since the beginning of time. Changes in the markets, same story other than the method of marketing as the rise of the Internet some years ago has radically changed the role and future of the local music store.
One thing that hasn't changed one tiny bit though is repairing and restoring guitars. I got my start by doing and learning about that at around the age of 16, several years before I opened my first store, fearlessly dismantling a 1940s Martin guitar that already been "repaired" half to death by more than one "professional", as in "professional wrestling". I already had a young lifetime of fine tool usage behind me and more than a little knowledge of wood and how it's grown and processed and the properties and usage of glues and other technical stuff, and I just couldn't wait to see what those Martin people had been thinking when they designed and built those things. I did get it back together successfully and to fine usabilty by the way. Within a few years I had become known as the "go to guy" for delicate and high-quality guitar repairs here in New York and that eventually led to opening a store, and I continued to do the repairs and restorations myself until I gravitated more off the workbench and onto the desk to run the business. But we still do things the same way here: carefully, thoughtfully, and thoroughly. Ain't no other way to do it if you're going to keep up your reputation as tops in a city like New York. Like I've said to so many people over the years who came in nearly in tears with the plaint "Can my guitar be fixed???!!??!!" "Of course it can be fixed. If men can be put on the moon any guitar can be fixed, long as you're willing to go all the way to get it done right". Some things never change.