I have a complicated relationship with Frost Death Knights. I started playing Blood DPS when that was a thing, but when Blood became a dedicated tank spec and the other two specs became dedicated DPS, I went two-handed Frost. I still main-specced as a tank in Cataclysm, but through Mists, Warlords, and Legion, I've been primarily Frost.
Now, I really prefered two-handed frost, with its massive Obliterates. So when they made it dual-wield only, I actually started Legion as Unholy, then went Blood, but then went back to Frost. The thing is, my favorite color is blue. I know that seems really minor, but I've gotten so used to my Draenei (blue skin) wearing blue-tinged dark armor, wielding a weapon with a blue glow, and having all my attacks cause bursts of blue death, that it's really hard to get back to thinking of Death Knights as having another dominant color palate.
And given that look and feel are basically the main appeal to video games for me, that's a big deal.
It is a difficult trade-off, wielding two dinky swords versus wielding a much more impressive runeblade. Basically the only real saving grace of the Blades of the Fallen Prince as an artifact weapon is that they literally used to be Frostmourne. Given the option to actually wield, somehow, Frostmourne itself in its intact form (and seeing variants on it the way that the other artifact weapons have,) I'd really prefer it, but I'll have to content myself with the swords made from it. Sadly, Blizzard feels that at least one DK spec should be a dual-wielding one, and with Blood as the tank spec and Unholy already having the whole "summoning undead" schtick, it's not terribly surprising that Frost got stuck with it. I only hope that in a post-artifact world, we can go back to using two-handed weapons (and maybe if we all beseech the Lich King like good little Knights we'll someday get a Frostmourne transmog piece. A DK can dream, can't he?)
Anyway, in the last few patches, the love-it-or-hate-it Breath of Sindragosa talent has been dominant - basically if you want competitive DPS as a Frost DK, you have to pick it and all the talents that allow you to sustain it as long as possible.
Thus Frost winds up being a kind of two-phase spec. You have the Breath phase where you desperately need to generate as much runic power as you can and get seriously penalized if you screw up or if you need to stop whacking the boss for a couple seconds, and the waiting phase where you just do the baseline Frost rotation while you wait for Breath to come off cooldown.
I'll be honest and say I've started to get used to this build, but the panicked resource generation required from the build isn't always what I want, especially given that I feel Frost, flavor-wise, should be more about being slow and steady (the "fight" against Arthas in Halls of Reflection is a great example of what I think a Frost Death Knight should feel like.) In fact, I could imagine a whole redesign of the spec that would have you build up Runic Power and unleash it in a massive single swing, but the point is that I don't know that Breath of Sindragosa fulfills my particular image of the spec's fantasy.
The changes they're making are fairly extensive - I believe the Hungering Rune Weapon talent is getting a bit of a redesign, and many talents are swapping around. The goal is not to nerf Frost in general (as far as I know they're not really exceptional these days) but to allow for greater build diversity, which is something I'm right on board with.