It's worth it if it keeps you motivated.
I've never spent big money (+$1,000) on a guitar or amp, never made a habit of buying $99 ones either (Squier '51's the exception, and a good little axe). I usually think ahead as to what I might want to add versus impulse buying because "Hey, what a bargain!!" comes along. Buying equipment you really want, and will use, is the key to staying motivated and enjoying playing.
That being said, if somebody is really gassing for a boutique amp and $3000 custom shop axe, and have the funds, I applaud them, go for it!
If, on the other hand, a Valvetronix and SX will keep someone excited about playing, great.
Most of my gear is good quality, which brings me to another point you made.
As far as my own personal tone, I've found when I start feeling "this should sound better", and thinking I need to buy something different...... it's usually about the same time I've hit a plateau in my playing and need to practice more and learn something new. That's just my personal experience, I'm not suggesting that about anyone else. But I did find it interesting that I'd buy a new piece of equipment, start practicing like crazy, thinking it had improved my sound, and then.....
go back to the setup I'd used 6 months ago and think "Hey, this didn't sound bad, what was I thinking?"
So ya, if it keeps you motivated, go for it. Quality gear, whatever the $$$ amount, is always worth it, IMO. But I really buy new gear (usually), just 'cause I got the G.A.S.
Now let me ask you this......
How do rate that Agile you have, because I'm thinking I need a Paul style guitar, and from the features they seem to be a better value than Epiphone.
Some of the Epiphone's are nice, but no ebony fretboards or abalone inlays.
Are the Agile's PU's, switches, hardware good, fair, poor...? If I wait to get a "real" one, I'll be saving quite a while, which kind of goes back to your original question.
If you were doing it over again, would you buy, say, a $500 Agile, or wait and get a $2500 Gibson?
Guitars
Wilburn Versatare, '52 FrankenTele(Fender licensed parts), Fender USA Roadhouse Strat, Fender USA Standard B-bender Telecaster, Agile AL 3000 w/ WCR pickups, Ibanez MIJ V300 Acoustic, Squier Precision Bass,
Amps
Ceriatone Overtone Special, Musicman 212 Sixty-Five, Fender Blues Jr., Peavey Classic 30, Fender Super Reverb, Traynor YCV-40 WR Anniversary w/ matching 1x12 ext. cab, Epiphone SoCal 50w head w/ matching 4x12 cab (Lady Luck speakers), Avatar 2x12 semi-open back cab w/ Celestion speakers
Pedals
Digitech Bad Monkey, Digitech Jamman, DVM's ZYS, Goodrich volume pedal