Good points, it might also be 1 additional proficiencies.
But don't pick something like Wizard's Arcana or Cleric's Religion as a basis for reasoning... First of all, while these are obvious choices, notice that no Wizard has to take Arcana proficiency and no Cleric has to take Religion. They are iconic choices, but if you think about it, they don't necessarily need them. A Wizard without Arcana is not crippled in any way, she just has a lower chance of answering questions related to magic, but she still knows the same amount of spells and casts them at the same power as any other Wizard. So the game doesn't have to grant 1 more skill to a Fighter turned Wizard just because of this... only to maybe see that player get away with another choice!
If you take the Fighter or the Rogue as a basis instead, you'll notice that none of their skill is as iconic as Arcana for Wizards or Religion for Clerics. Rogues' skills altogether are iconic (in fact I'm positive that when you multiclass into Rogue you'll get 2 more skills), but not a single one is so essential that someone shouldn't be a Rogue without it. Fighter skills even less so.
About score requirements, we have to see what are the numbers. If they are too low (13 or less), then IMHO they should have scrapped them altogether. If they are significant (15 or more) then this is actually a system for preventing heavy multiclassing.