Having a package registry has its advantages and disadvantages (npm) but nest.land is trying to make the best of both sides, a very common complaint with deno is that it does not have a package manager or official registry. The nest.land team took as a axis to use blockchain as a central technology, which in my opinion is a serious decision, since problems such as left-pad would no longer occur since the packages are immutable, in the case of packages they have a system package reporting which mitigates malicious packages very well.
regarding whether or not deno should handle packages with url is a dividing issue, first of all deno does not try to be a direct successor of nodejs, it tries to be compatible with the browser, in the browser it is imported using directly url, some solutions are, use a deps.ts file and have all the import there, use import maps and maybe manage them using Trex, in order to change the paradigm is crucial to move forward, many when nodejs was presented did not like the idea of server-side javascript, Today the nodejs ecosystem is one of the most important in the industry