It's clever to stop the combo for obvious reasons, but then we are back to he dies fast and perhaps in a ridiculous way without harming the player characters as you've described.
Clever but not easy, players need a spellcaster with wall of force prepared because Strahd can automatically escape a grab with shapechange, and the vampire can try to make him lose concentration. A group's victory under the circumstance they have the tools to stop the combo doesn't change a bad design, for one victory there could be countless defeats with awful and anticlimatic fights.
I'm not convinced that you're right about a fight with Strahd being anticlimactic.
But, also... anticlimactic does not equal awful. "Anticlimactic" fights with "boss" enemies can actually be great fun in an RPG.
A story my players still tell, from a D&D3.5 Colonial-themed Swords & Muskets game, was fundamentally anticlimactic. The party was on the run from a savage tribe of native Ogres, holed up in a small fort on the frontier. The ogres were assembling at the treeline. A few shots were fired by the defenders, before the ogres initiated an impromptu parley calling for the release of a prisoner the party had taken. In short order it was clear parley was going nowhere, and I described the ogre tribal chief as he emerged from the trees. He was going to give an ominous short speech and then send his ogres forth in force to smash the walls.
One of the party, a mute semi-retired bandit, decided at that moment to pop up and take a shot from his double-barreled flintlock. I told him it would be a long shot, but of course he was welcome to roll the attack.
He rolled a crit, an insanely effective one, and blew off the top of the ogre chief's head. The ogres freaked and backed off, and the big battle that we were building to completely fizzled out.
I won't deny I found it a little frustrating, as I'd sunk some time into designing that ogre. He had druid levels!
But the party was laughing their butts off, and very pleased. The ogre tribe eventually regrouped, and came after them even harder. But in that moment, it was fundamentally anticlimactic. And a lot of fun.
It can cut both ways, too. In the same game, when a PC Dragon Shaman/Monk charged into close combat with renowned bandit lord Bloody Blake, she expected to get into a ferocious melee. Instead, he pulled out the minor artifact gun that gave him his moniker and shot her dead. The player wasn't too pleased with that outcome, and it probably felt pretty anticlimactic... but they eventually got Blake.
Anticlimax isn't really the enemy. If anything, I think it's sometimes necessary for a world to maintain verisimilitude. Sometimes the party fights their way through the Necromancer's defenders and burst into his laboratory for their epic confrontation... only to find that the necromancer buggered off twenty minutes ago when he heard them start their assault.
Edited to fix a typo.