Force Weilding Knights with Lightsabers able to cross a Galxay in less time than it would take to drive across the country and this bothers you?That bugs me every time. there's nothing on that claw that looks like it'd connect and interface.And why is he always using his claws instead of an actual scomp probe? Just weird.
I think they have the technology for nano-connections built into it.
It's a question of consistency. We expect probe-like attachments from astromechs being used to plug into a computer because that's what R2 has done in like every movie. When chopper uses a very obvious claw attatchment it's almost like R2 using his periscope to weld something, it's possible but it doesn't 'look' right.
Also the writers for the Rebels are the same ones that worked on the Clone Wars and they worked very closely with the source material because they are bigger Star War nerds than we are. They also worked next to George Lucas throughout out the making of the Clone Wars which lasted a number of years, so I think they know the Star Wars Canon better than we do since they are writing some of the Canon and they have to work closely with the rest of the Canon now. Disney is not letting writers create anything now, they need to collaborate with each other before it is signed off.
But that is my take on it and I am going by the fact the EU is not a reliable source anymore. Rebels is Star Wars now and everything in it is Vetted Canon now.