Voyager, or more precisely the Intrepid class is in fact a design built for combat performance.
Voyager is an exploration vessel like most other frontline Federation ships. It's just as "built for combat" as the Galaxy-class, except it's slightly better at it because it doesn't have all that extra shielding around the nursery.
Quite the opposite in fact. The Federation President on DS9 did refer to Starfleet as a military a few times in the Homefront/Paradise Lost story.
Nope. He uses the word "military" exactly ONCE, and then by way of comparing Earth to Deep Space Nine.
And I will point out, the two in Star Trek who have called Starfleet a military are the all-knowing omnipotent being (Q)...
Who also refers to humanity as a "dangerous savage child race" and refers to Guinan as "An imp." he may be omnipotent, but he's also about the farthest thing there is from a reliable source.
I always wondered how they planned on holding a Federation core world with 25,000 troops?
That was kind of my point earlier: actual military forces in the 24th century probably rely heavily on automated weapon systems that act as tremendous force multipliers, allowing a squad of four or five soldiers to do what in previous centuries used to take entire batallions.
Even in the 23rd century we see Kirk launch what is essentially a multi-kiloton grenade at a Gorn force attacking them from well out of visual range. I'd like to think that the effect of that little grenade was more flash and excitement than actual power, but I would be very surprised if this is the case; in "Omega Glory" we hear Ronald Tracy saying "We killed THOUSANDS and they still came!" meaning even standard side arms can give a small force unparalleled destructive power.
So those 25,000 Romulan troops wouldn't be the problem; the hundreds of pieces of field artillery, ground-to-orbit defense batteries, portable shield generators, cloaking/camouflage devices, plasma torpedo launchers, ground and aerial vehicles and god only knows how many automated weapon systems... THOSE would be a problem.
Call me biased, but many a time I've thought about the Systems Alliance from "Mass Effect" being a good idea of what a 24th century military would (and probably does) look like. Specialized weapon systems with specialized and diverse settings beyond "stun" and "kill" (e.g. incendiary, armor piercing, disabling, etc), personal forcefields as standard infantry kit, body armor capable of shrugging off close range detonations and high speed impacts, integrated sensors, battlefield network systems, rapid deployment systems (the Mako kicks ass like that) field artillery and fire support (the Mako ALSO kicks ass like that) and various types of heavy weaponry that make Insurrections "Worfzooka" look like an airsoft rifle. With the kind of technology we SHOULD be seeing in the 24th century, a specialized military force would pretty damn impressive. Trouble is, it would also be very VERY limited in its capabilities; they'd be HIGHLY over-specialized in planetary defense, area denial, siege warfare and mixed unit combat tactics, and very likely to find themselves out of their element in fighting an enemy using unconventional tactics or unfamiliar technology (or both). The Romulans, of course, wouldn't have this problem when going up against a known quantity like the Vulcan Security forces or whatever the Federation has for a land army.