To be fair to Milligna, one of the creative tensions in comedy is contrast. Often it's between the banale real world and where the comic is at, and he was at a sometimes painful extreme. Sellars and Secombe on their own showed distinctively different faces, rarely ever reaching the rarified heights of the Goons, which shows how they moderated his angle into the different charactrisations. Without Spike's extreme starting point, we'd have lacked the language of comedy which TW3, Monty Python and ISIRTA came from. If anything, we need more now, we've got a bit tame.
What should also be mentioned is the contribution made by Michael Bentine in finding this balance in the first place: that touch is entirely his, although he did not stay with it. For example, it was Bentine who introduced Ruxton Hayward to the rest, giving them the materials which so magically transmuted into Sellars Bluebottle. Yes, Bluebottle was based on a real scoutmaster!