Because there is nothing that should be considered 'beginner'. Every ship should have a purpose...
Yes indeed. And the purpose of the Eagle and Sidewinder is to introduce new players to the game. Two ships with which new players can smash and destroy to learn about insurance before they get an Asp and a fatal collision
really hurts. Two ships that teach new players the intricacies of outfitting, without costing an absolute fortune to modestly upgrade. One ship that has a purpose in being the beginner vehicle when you're aimless, penniless, and harmless, and one ship that you can buy pretty quickly after 2 or 3 missions from a faction, so you learn a bit about shipyards and what a new ship entails.
They have a purpose, a very important purpose. Let's not ruin that purpose and start wrecking ship balance. Launch Python notwithstanding Elite has a pretty superb balance of ships at the moment.
I think the answer to your third question/statement can be found in your second one. By buffing the beginner craft, they could fool unsuspecting PCs and catch them off guard.
So every time I am taking my Type 9 on a hauling trip I have to worry about running into ships the size of bugs because they've possibly been upgraded with some magic tech (that doesn't seem to be available to more advanced ships)? That'll make the feel of the game a bit ridiculous, to see Sidewinders taking on and smashing allcomers with ease.
Furthermore, the Eagle doesn't actually need a buff.
[video=youtube;riR3A5PrI3A]https://www.youtube.com/watch?v=riR3A5PrI3A[/video]
It just needs skilled hands.