Well, a ten year old Han almost did make it into ROTS, and removing that plot point was probably the best decision in the entire movie. Because, yes, I agree that all these convenient meetings ruins everything, especially with the droids. Granted, having the droids be in all the movies was something Lucas had toyed around with since the beginning, but I don't think he should have done it. Or, if he had, he should have had them being observers, removed from the events and characters but just happen to be nearby some major events on occasion. A cutaway to their confused opinions and then back to the main action. As much as the droids annoyed me by the sheer improbability of their being there, and as annoying as it was that the less than creative mind wipe was used to preserve continuity, I don't know what else they could have done from that point to fix it. However, it really pisses me off that they didn't erase both their memories. It totally changes R2's motivation in Star Wars. Rather than following Princess Leia's programming, he's now trying to get the old gang back together to save the day. And it just makes him seem like an insensitive prick to be sitting on all this important information and just not tell anybody. When Ben Kenobi said he didn't recall owning a droid... he meant it! To interpret that look at R2 as some kind of secret understanding is ridiculous and makes even less sense. What motivation would Kenobi have to keep his "previous" relationship with R2-D2 a secret? I don't even know if I could come up with a rationalization for how that makes sense.
But, yeah, too many convenient connections. Chewbacca and Yoda fighting in the war together. Owen Lars hanging out with C-3PO (and did anyone notice how Anakin and Padme just took off, stealing the Lars's droid without even saying goodbye or anything?). Little Boba Fett shooting lasers at Obi-Wan Kenobi. Even Padme plotting with Mon Mothma was better left on the cutting room floor. Most people seem to think these Rebellion scenes would have befitted the movie... and, of all the coincidences I mentioned, this one would have been the most plausible... except for the fact that they'd already put far too many of these strange occurrences throughout the prequels so that by the time you got to ROTS, seeing them together would just be one more hurdle that your suspension of disbelief just couldn't jump!