I didn't think Jacob was boring so much as he had a stick up his arse most of the time, but to be perfectly fair he was
the only actual military type out of all the main cast and somebody had to fill that role. I think one of the many improvements of ME2 over the first game was the inclusion of the loyalty missions that let you get some insight into each character. I think there were some character associated side missions in ME1 but as I recall they were pretty forgettable and all just the same kind of copy/paste mission were you clear out that same damn outpost that all the other side missions used.
In fact they're so forgettable I can only recall Garrius and Wrex's missions; track down the evil doctor and find some old Krogan armour respectively. I'm not even sure any of the others even had associated missions.