Um, you don't check the schematics of your dev board before using it? 
How do you think i found the issues? Because i checked the schematics! You however assume i was a reckless
irresponsible who just powered up ST boards on the terms of ST
Code and Play attitude trusting ST?

PA2 and PA15 pins are USART and are by default connected the ST-LINK pinks so that you
can have the virtual COM port functionality (saving you the need for an extra FTDI dongle).
Kind of obvious
if you read the manual but point is UART is set to PP/High
they should have set it OD and PU. It's not PA15 it is PA3. Dont you read data sheets?

LED is on PB3 and PB2/PB8 are tied to ground by a jumper, because they apparently
serve as additional Vss pins (odd, need to look up the datasheet on that).
LD2 is on PA5. Dont you read data sheets?

DAC to AG via resistor and LED is just bad design practice, there are plenty of other pins ST could use.
There are plenty of pin cross connections just waiting for a drunk P-P operator.
However, all of this is clearly visible from the schematics and is marked in the manual as well and all these pins have solder bridges to enable/disable this functionality. So if anyone causes multiple failures, it won't be the drunken P&P operator but the
user of this board that didn't do their homework, IMO. 
And yet as proved you dont make your own homework before whine on others!
Besides no one said it's its visible or not, point is it's designed to eventually cause trouble all depending on the P/P operator drunk
or not. Example of drunk operator already happen about 2 years ago ST programmed F378 without USB boot, they recalled millions of
chips from supplier chain to reprogram. So yes ST do screw things up, and its not always visible from schematics and its kind of
naive approach you have thinking everything is OK with ST. No point in defending ST just because your french!

That's why you have to read the Nucleo product manual all way through!
However to ST credit majority of Discovery boards is betterly done.