Not being in the CL also means that you have to overpay on player transfer fees and wages, arguably for lesser players, players that may not come good. As well as price money it impacts your brand too, and your sponsorship deals.
For us specifically, over the period that Liverpool have been in decline we have greatly improved on and off the pitch. Our new stadium combined with our challenging for honours, and gaining CL football, is going to see us close that gap off the pitch which is going to make it much harder for Liverpool to challenge us in future years. Utd have not been out as long and are much bigger so can absorb the effects for some time.
One season out of the CL is not as bad as two, or three, or more. I see the problem kind of compounding over time, having greater impact, so I really hope Liverpool miss out again.