I don't see why working away all week would make him a disinterested parent on the weekend, IF you let him take charge or share duties when he is home.
My husband works away all week, so the time on weekends, the children are prioritized. He does the ballet and piano runs, takes them shopping with him (to get screws or WD40 or some such excitement) or visits friends with them. I get at least one morning or afternoon a weekend to myself to work or have a nap.
However, the big difference is that he was a hands-on parent before, so it comes naturally to him now, but it didn't initially. If asked, he would always let me change the nappies, bath the baby. I took the advice of a good friend to literally abandon him with my first, I was working weekends at home, so packed them a lunch and shoved them out of the door for the day. That was the making of his bonding with his first, then he discovered he loved spending time with his children and actually stayed home three days a week (and worked nights) with his second daughter.
He's probably lost a bit of confidence in being able to do it, and you look the confident and competent one, so get him to take one of the children out on a trip (even for his hobby or anything). Get him to take an active part in deciding what to do on weekends and to develop shared activities or just time to walk and chat with them.
Finally, I take the point of Valhalla and others that you don't need two identical parents to be happy. If you adore him and the children do too, perhaps they are happier with the bond they have than you might think. Perhaps for them, it's about daddy being around and watching what they do, and taking an interest every now and again, and being a reassuring presence on the weekend. You don't have to interact in a full-on way to have a bond.
As for the activity he let you down over, more fool you. You know he works long hours and can't really leave early on a Fri, I would have got on with the event without him, he can't have been crucial to it and if he was, it was a bit silly to construct it that way. He does sound like he has a lot going for him in many ways.