Agreed, a huge loss, irreplacable.
The Two Ronnies often seemed - superficially - to be "all tits 'n bums" (the "classic" British dirty postcards obsesssion, Benny Hill, Carry on films, etc). But, if you look at the quality of writing, it was extremely high, many of the sketches being intellectually very witty (something you'd usually associate more with Fry and Laurie, etc).
I wasn't too fond of his "situational" humour, eg Open All Hours, but certainly Barker was "inspired" casting in Porridge.