...and?
What's the point of any of that stuff? Take no damage from creepers? Kill zombies with one hit instead of two? The only good thing I see in that list is the jetpack; everything else makes an easy game effortless.
The point of Vanilla is exploration: seeing just how huge a random cave goes, discovering an underwater mineshaft, scoring big with your dungeon loot, carefully digging for diamonds on the edge of a lava pit. I know I feel satisfaction when I uncover a mother lode of gold deep in a cave. How much do you feel when you stick dirt into a diamond generator and flip the switch?
I'm not sure you understand just how difficult it is to build the 'diamond generator'. By the time you have stuff like that running at and reasonable speed you would already be DONE with everything vanilla minecraft has to offer. Mods like this let you do anything you want in vanilla minecraft, and then when you get bored of YET ANOTHER CAVE/MINESHAFT/RAVINE then you can move on and do something else instead of going "Welp that's the whole game gonna go play TF2 now."
Huh. From the way people discuss Buildcraft or whatever, I had a different image in mind: You throw together your alchemy bench and solar collector (out of wood, of course), turn cobblestone into iron, iron into gold, and coal into uranium, before putting it all together into an infinite food generator and an automatic mining robot, and maybe a self-repairing house made of solid obsidian.
FAKE EDIT: Gold is used in watches (telling time underground) and powered minecart rails. You could also make blocks of solid gold if you wanted to be ostentatious.
(wow, I spelled ostentatious right on my first try

)