I wasn't just meaning the Borg, though I didn't express it properly in what I wrote.
The Dominion made chowder out of Mirandas and Excelsiors that the Federation was forced to use for lack of ships, because they'd just stuck with those designs for far longer than was wise and didn't move to replace them with something more modern when they were swimming in time and money.
Even talking TnG-era, they didn't really have any great number of pocket warships; the Galaxy and Nebula-class were powerful, but given their size the amount of military hardware they bore was actually very low. (Somewhat dependent on your canon stream) ships of the TnG era were shockingly stagnant in terms of what military hardware they did mount. Suddenly, after getting their teeth kicked by the Borg, Starfleet was cranking out quantum torpedoes, small ships with burst-fire torpedo launchers, next-gen shields, articulated nacelles, bio-neural computers, pulse phasers and ablative armour. They had the ability, they were just so arrogant and so accustomed to long-term peace they forgot they needed to be ready to protect the Federation.
I guess I'm saying we should be careful to maintain our military technology going forwards. We need up-to-date fighting ships even if we don't anticipate imminent hostilities.
I've said it before, but I'll say it one more time just 'cuz I think it's important; if we get a design that's not actually a warship and is a limited production run, budget permitting it might be worth investing in experimental combat technologies such as light covariant shields etc because that brings the technology forwards, and it doesn't really matter if that part of the design flops. On a warship, it does matter if we go experimental and it flops.