Weak argument for Paladin benefit.
Fighter has same access to UMD as a paladin.
They just usually chose not to invest in CHA for UMD and invest more to str or con.
Fighters also have the feat room to take UMD+3 if they really wanted to.
Arty Scrolls have had their UMD levelboosted so most are in the UMD40 range.
Trying to UMD with no concentration while you are tanking is not overly usefull.
As skill points go Paladin and Fighter only get 2 per level + Int Bonus.
Assume 11 start for CE and a +2 tome puts both at 13 possibly 14 for 1-2 more points invested in a cross class skill. Maybe 1 more if human. so average of 4 skill points per level.
Class skills, Fighter - Intimidate/Jump ,Paladin - Intimidate
All other usable skills are cross class - Balance/Jump/UMD.
Not a lot of room for UMD investing without significant gear swapping and only really viable at cap.
Using UMD would only be usefull if splashing a couple rogue levels.