I see it both ways. Start adding up everything to get a chassis updated w/all the wants: better geometry, better steering, lower center of gravity, better braking, bolt-on items that are designed to work together like a new car chassis. Suspension packages that work well aren't cheap. Some offer re-engineering of the geometry to improve things but are still bound by the factory chassis' pick-up points which were a compromise. So you spend money to improve things but the factory limitations hinder the bang for the buck.
I always look into the aftermarket stuff when I hear/learn about it just to see what/where the improvements are done. A chassis w/a better design that you can drop a body over is a great way to go if one can afford it. It's crazy once you start adding it all up how much piecing together upgrades cost. The difference is the ability to spread it out over time vs one big purchase. But, if a guy is spending 5k for a front suspension set-up w/better geometry using the factory pick-up points (new steering gear, arms, spindles, brakes, sway bars) & then 3k for the rear (housing, rear suspension that again is based on the OE pick-up points; brakes, sway bars) but will be limited on tire clearance & still requires chassis bracing to get the most out of the upgrades paid for on the flimsy stock rails, that gap between the two options starts closing in fast.
Like I said, I can see it both ways. If a guy can afford the full chassis route, it seems the better option depending on the price tag. I priced out a Schwartz chassis.... It came out around $17 w/the options selected (it was a wish list thing). No way I could justify 17k for a chassis under a street driven g-body. A higher end build would be a different story. Roadster Shop has multiple 'series' of their chassis which range from 10-20+k. I could see the value in the 10k end of things from my blue collar perspective. Not sure which end of the spectrum their g-body chassis will be.