"Thinking" is perhaps generous if this is what it entails. But sure, make the biggest changes to UK government functioning and UK trade in the middle of a unprecedented national and global crisis. "Brave" as they used to say. 
The most "fundamental policy problem" the UK government has yet to decide is if its prepared to make concessions in return for trade deals. That applies to the US (food), EU (level playing field), Japan (car tariffs?) etc.
Then there are the numerous individual policy decisions to be taken in a trade agreement. Individual rules of origin, levels of inspection, rights to temporary workers, the way government regulates. All to be decided on current plan in the middle of a pandemic.
If the UK government goes ahead with the plan to not request a transition extension everything that goes wrong in the economy after this December can, fairly or unfairly, be blamed on that decision. That's why this should be such a big decision.
