I see that you installed network manager applet's icons in the correct way, that is in the hicolor icon theme.

This is good. However, these icons do not scale well with bigger panel sizes (or DPIs, or screen resolutions, or whatever).

Who designed those icons? Would it be possible to ask for higher, alternative resolutions or better, SVG icons to complement the 22x22 "pixel-perfect" sizes?

The offending icons:
/usr/share/icons/hicolor/22x22/apps/nm-no-connection.png
/usr/share/icons/hicolor/22x22/apps/nm-device-wired.png
/usr/share/icons/hicolor/22x22/apps/nm-adhoc.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting01.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting02.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting03.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting04.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting05.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting06.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting07.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting08.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting09.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting10.png
/usr/share/icons/hicolor/22x22/apps/nm-stage01-connecting11.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting01.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting02.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting03.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting04.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting05.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting06.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting07.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting08.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting09.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting10.png
/usr/share/icons/hicolor/22x22/apps/nm-stage02-connecting11.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting01.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting02.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting03.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting04.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting05.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting06.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting07.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting08.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting09.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting10.png
/usr/share/icons/hicolor/22x22/apps/nm-stage03-connecting11.png
/usr/share/icons/hicolor/22x22/apps/nm-signal-00.png
/usr/share/icons/hicolor/22x22/apps/nm-signal-25.png
/usr/share/icons/hicolor/22x22/apps/nm-signal-50.png
/usr/share/icons/hicolor/22x22/apps/nm-signal-75.png
/usr/share/icons/hicolor/22x22/apps/nm-signal-100.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting01.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting02.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting03.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting04.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting05.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting06.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting07.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting08.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting09.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting10.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting11.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting12.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting13.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-connecting14.png
/usr/share/icons/hicolor/22x22/apps/nm-vpn-lock.png