For everyone wanting evos for Kricketot, Ariados, and Ledian, regional early route Bugs do not get addition evolutions, just like regional rodents and birds, for traditional reasons.

For everyone wanting evos for Pokemon who have base stats over 465 (Camerupt, Skarmory, etc.), they're already competitively usable in OU, so there's no need to give them unnecessary evolutions. Just because it's happened to only a few Pokemon (Scyther, Rhydon, etc.) doesn't mean they'll do it again.

For everyone wanting new evos/pre-evos to Kanto Pokemon (Sandslash, Pinsir, etc.), the chances of getting another Gen 1 remake with an updated dex to include 190 Pokemon, including all the cross gen evos/pre-evos to Kanto Pokemon, is possible, so it's important that Sylveon is the only Kanto cross gen evo in Gen VI, so would help GF add more Ghost and Dragon types into the updated Kanto dex, in order for Agatha and Lance to have better teams.

It's best to focus on giving pre/evos to non-Kanto Pokemon, who do not fall under any traditions/patterns, such as Corsola, Sableye, and Chatot.