Why is TOGA thrust 'never' 100% N1?
Why not make 94.5% read as 100%?
94.5% tells you the margin you have. It will be closer to 100% in high-thrust versions – or even higher, i.e. the limit is pushed as the thrust ratings increase. The PW1100G you're asking about, its thrust varies from 110 to 150 kN based on the installed version.
For example, the A321's 150 kN CFM56-5B3 exceeds 100% near sea level and in cool to moderate temperatures, unlike the 120 kN -5B4 (both tables below).
Note that nowadays whatever the installed takeoff N1 limit is, it's rarely limiting – meaning the engine will reach the EGT limit before it reaches the N1 (barring major failures).


Source: A321/A320 FCOM