The Crimean bridge was in occupied Ukrainian territory. I guess they have a right to blow up what's supposed to be theirs. Duh!
Well to be honest: it was built by Russia across the sea channel.
It is a prime target for Ukrainians for last 4 years.
At first that bridge was essential to have Crimea connected with Russia mainland.
Now the bridge is not of vital importance, because Russians created a land corridor to Crimea by annexations of eastern Ukranian regions.
It does remain a prime target for Ukraine, for propaganda purposes.
However, 4 years under attack, the bridge still holds.
It (prima facie) says something of Russian air defenses. While the air defenses in the modern day of drone swarms and combined missile attacks are not perfect (we can think of other recent examples), the bridge still standing does say something beyond daily propaganda of Russian air defenses.
The Kerch Strait (where bridge is located) and Sea of Azov are considered “internal waters” by both Russia and Ukraine under a 2003 bilateral agreement.
That means:
They are not treated like open international straits (such as Gibraltar or Hormuz).
Navigation is regulated by the coastal states, not freely open to all countries.