And clearly as a mage you used your interrupt on every single boss for CE. Mage is lucky in not having to spec into counterspell, which is a nice bonus, but claiming having the interrupt as a talent isn't a choice is pure delusion.
"I'm so glad I have my interrupt for Skolex, it adds so much to my contribution" - delusional.
There will definitely be cases where people mistakenly miss an interrupt for certain content, but it's all repeatable, so you change spec and go again. It allows people to learn and adapt to the content.
Most defensives are not competing with DPS throughput, with few exceptions (netherwalk/cauterize) it's usually defensives vs utlity which is a good tradeoff imo.