Tasking cannot be defaulted to.
Tasking is used for Sprites. Compiling them. Registering them. Recompiling them.
Deckers don't have access to sprites and they do just fine, but this mean you no longer have access to sprite powers such as Camouflage, Cookie, Diagnostics, Electron Storm, Hash, Override, Phantom, Stability, Suppression, Trap and Watermark...... :-(
Same as Tasking, Cracking cannot be defaulted to.
Cracking is used for Crack File and Disarm data bomb. Which mean that without Cracking (and without Tasking) you don't have any method of removing the file protection nor disarming data bombs (to be honest, this is probably a show-stopper).
Cracking is used for Data spike, Tar Pit, Crash Program as well as Resonance Spike. Which mean that without Cracking (and without Tasking) you don't have any method of bricking devices or programs or generally causing matrix damage.
Cracking is used for Snoop. Which mean that without Cracking (and without Tasking) you don't have a way to eavesdrop on communications or snoop on live camera feeds.
Cracking is used for gaining access on networks (either via Brute Force or Probe + Backdoor Entry). This mean you can't take several Electronic actions (such as Format Device, Reboot Device, Trace Icon, Jump Into Rigged Device, ...)
Cracking is also used for random actions like the Hide action and the Jam signals action, but they are not really that important I guess.
Having said that, there are also a few actions you can sort of still emulate;
An alternative to Check Overwatch Score action would be to learn and use the Emulate (Baby Monitor) complex form.
An alternative to Spoof Command (and to some extent Control Device) would be to learn and use the Puppeteer complex form (if the device is on the inside of a non-public host then you also probably need to first establish a direct connection to the device).
An alternative to Edit File action would be to learn and use the Editor complex form (but I don't think there is a way to establish a direct connection to a file that is on the inside of non-public host and I also don't think it let you bypass data bombs or edit files that are still encrypted).
Overall I would suggest against skipping both Tasking and Cracking. At least if you are the only Matrix Specialist of the party.