If/when I get married, my plan will look like this: majority of life insurance via term, modest WL policy, disability income insurance, some index funds, and some stock of two or three companies that I know deeply.
What happens to folks who retire after a crash like in 2000? It'd probably be better if they left their investments alone, and instead drew some money from their WL policy. You could argue that their allocation should've been well tilted from equities at that point, but what if it wasn't?
In a perfect world of automatic 10% yearly returns, and diligent saving/investment, buying term and investing the difference (from WL) would smack the performance of WL. Unfortunately it doesn't work like that. Most people don't save/invest diligently, and the market isn't automatic.