It’s mainly that they can do amazing tricks with wavelengths. You would never be able to see the galactic core because of the dust in between, but infrared has a longer wavelength than the dust particles themselves, so they become invisible to it. Pulling that off is tricky, though, since the lower the wavelength, the harder it is to focus on the source. That Spitzer is able to focus so precisely and yet get wide angle shots seems to be the amazing thing here.
The lower “frequency” the wavelength, that is. Without it’s misleading.