While I agree Sky have gone over the top the tie has always been labelled as the north west derby - I would suggest that it is a massive game between the two most succesfull clubs in this country with the biggest fan base therefore the market for both sides is there - Liverpool through the 80s and Utd thereafter - there is a fierce rivalry between the two clubs and I would bet you anything you like of you was to ask a fan of either club what is there biggest game of the season then both would say this game. Its born out of respect ultimately for what either side have achieved.
Im a 40 something year old man born in manchester in the mid 70s and supported Utd through the 80s when Liverpool won everything in fact the vast majority of my mates are Liverpool fans due to that reason - I was brought up watching Liverpool dominate and despised there glory (Jealousy) and likewise Ive seen the same hatred towards Utd in latter years when weve been sucesfull.
The rivalry between utd and city is nowhere near on a par most city fans have only jumped on the band wagon in recent times and as such there isnt the same competiveness to the fixture and likewise I would suggest Liverpool-Everton are often split between families and the rivalry is different where as utd v Liverpool in the main is hatred so I can see why Sky are doing it.
I had a season ticket for many years and have been fortunate to see Utd play in many of the biggest stadia in Europe - San Siro, Bernabeau, Nou Camp, Allianz, Celtic Park as well as all of the recent premier away grounds and Ive never been more intimidated than going to Anfield the atmosphere as an away fan there really makes the hairs on the back of your neck stand up - Ive been pelted with coins and been locked in the ground for 90 minutes after and trust me that police escort back to the station is scary - I assure you the atmosphere is Vile between the two sets of fans and Id never take my kids to an away game at anfield - Again I think theres an under currant of respect at the core but there is no other game like it if your a fan of either side.
Look at the amount of business the two clubs have done with each other the years 1964 was the last time the two clubs did business - look at how players have left and then joined the rivals as an example look how Liverpool fans view Owen or Utd fans view Ince as an example, it is without doubt the most important game of the season to both clubs all be it not the most vital and I think its as close as you will get to Celtic Rangers in the UK (Im sure the geordies would disagree, or the Spurs v Arsenal Derby as an example) but as a UTD fan definitely not the case
That said Sky are completely milking it ......
PS Utd 2-1