No matter how you slice it, no matter how much higher the resolution is on a 15" rMBP, the fact remains: I would have only two undesirable options: a) attempt to view the same amount of stuff on a 15" as I do on the 17" - but that will make everything smaller. or
attempt to keep everything the same physical size - but then I would have to scroll, to see the same amount of stuff. Neither of those things are options. No amount of pixels per square inch will ever change these facts. It's not a good option.
Why do I need 17" of visible space?
1. I am a professional database engineer, this is how I earn my keep. I simply need a lot of screen real estate. I want that real estate plastered across 17 inches, not 15 inches. I need to see a whole slew of things at once arranged on screen in readable sizes, to make my work smoother without fidgeting with additional zoom gestures.
2. On the side, I play around with music composition. DAW software loves to have all sorts of stuff everywhere on the screen.
3. I love watching HD and blu-rays in my (obviously modified) 17" MBP. 17 inches sort of crosses the threshold that goes from annoyingly small (15"), to a somewhat entertaining and acceptable size to watch a movie.
And about the new rMBP in general:
4. I actually use all of those supposedly useless plugs along the side, on a regular basis. That's right, I do use them. Transferring large music projects to inexpensive and readily available firewire800 drives is much faster than going over wifi. Thousand-dollar, perfectly good, awesome firewire audio interface needs a firewire port. When working on hosted, extremely delicate database schema: better connect to solid ethernet, the last thing I want is a faltering wifi radio signal when writing new schema to a live solution in use by hundreds of people. This is the reality I live in.
5. Optical drive: a 50GB blu ray with 7+ channels discreet audio beats the pants off of a 5GB "HD" movie download with highly compressed video and only stereo audio, I don't care how you twist it, the visual clarity can not be compared. Also, an audio CD offers me 1,411kbps of music quality while the highest aac and mp3 only allow 256 and 320kbps respectively, which only goes downhill if remixing the audio (something I do for fun, yes). Generating inexpensive DVD-Rs (which can be legally bates-stamped) with data dumps for work is an extremely convenient tool. Archiving all of my recently purchased MP3s and CDs to an inexpensive DVD-R makes sound and safe sense (without having to downsample them for the cloud). Yes, I still have plenty of valid uses for the internal blu ray burner. Not everyone needs this, also not everyone cares as much as I do about sound and picture quality, not everyone is keen on making solid backups, and that's fine, but not for me. So make it an option, please.
5. I also like to boot from a nice fast Solid State device just like the next guy, but mine is in the Expresscard34 slot (Wintec), I still retain the large cavernous 1TB hard drive for all that high quality media, AND my (internal blu ray UJ267) optical drive. I want all three, and I have all three inside of my 17" machine, but this is no longer an option in the current lineup.
6. The new rMBP is no longer thinner and nicer when my briefcase would now need 8 dongles and attachments to keep track of, instead of the usual 4 (various video for work). Just give me the CHOICE to carry around a laptop that has everything already neatly built into it, let it be a few mm thicker, a couple pounds heavier, with a much bigger screen and fewer dongles hanging off of it.
7. Soldered RAM. I have heard "will you ever need more than 16GB of ram?" Well right now, no. But that's similar to what the salesperson told me when selling me the LCII "Will you ever need more than 2MB of ram?". Same for my LC475 "Will you ever need more than 4MB of RAM?", followed by my G3 "Who would ever need more than 64MB of ram?", the G4 "You'll never ever use more than 512MB of ram". The core 2 due "2GB of ram is plenty!". All of those machines were subsequently upgraded over their life cycles to 4-12 times the original RAM amounts. Today we are being told "You'll never need more than 8 or 16GB of ram". For someone who has seen it happen this way too many times, this is obviously bad mojo. I've also had ram go bad. It's rare, but I'd rather pop out one chip, pop in a new chip and keep working without having to ship off to Apple and have them solder me a new one.
This is not about being stuck in the past. This is about greater functionality, greater expandability, greater ability to negotiate various work environments, highest quality media (not lower!), and greater work productivity.
That said, the new rMBP is a great machine, it's just not what I need out of a pro machine. Call it a Retina Air instead. Then let a fully-endowed 17" be a true "pro" option, with or without retina, for those of us who enjoy and/or depend on it.