I would love to have the rule that multiclassing must be within a level difference between classes, but those characters suck.I love that list, minus multiclassing. I have never minded the dip. I do think there is room for improvement though.
One solution is to have multiclass characters dual levels at certain point.
5th level multiclass is 3/3 split, but with 3/2 HPs, and HDs, 5th level proficiency bonus. Only getting class features of both classes at 3rd level
8th level is 5/5
11th level is 7/7
14th level is 9/9
17th level is 11/11
20th level is 13/13