Dangerous Bc4!!!
2. 5. ... Nxd5 is the bad move rather than 3. Bc4 being the good one. It allows the Fried Liver Attack (6. Nxf7 Kxf7 7. Qf3+ Ke6, which is how it typically goes, with Black preserving the piece advantage in material for an awkward defensive position), as well as the 6. d4 Lolli Attack, which does offer White some advantage.
Might I suggest curbing your enthusiasm a little.
White has a 1-pawn advantage and Positional Advantage!!
I agree with your assessment after 7...Ke8, but what about 7...Ke6 ?
why wouldn't black just play Bc5 playing the Guioco Pianissimo opening?
Some dont play 3....Bc5 because they fear 4b4 !? the evans gambit .
After 3. Bc4 Black also can play 3. ... Be7 - Hungarian Defense in order
to prevent sharp theoretical variants.
or 5...b5!?
Also 5....Nd4 is very playable but I believe theory favors 5....Na5 but after 5....Nxd5?! 6 d4 ! is stronger than 6 Nxf7
why wouldn't black just play Bc5 playing the Guioco Pianissimo opening?
Yes, it is also possible. But I prefer two knights defense.
two knights is good option i agree.