Those are all good points (++).

Nevertheless, I remain of the opinion that using sudo only when actually required does help to minimise the possibility of problems arising. Such problems may be caused by malice but also by incompetence either on the part of the distributor or on the part of the user (such as running the command in the wrong directory/window/VM/whatever or just with a typo). It is (IMHO) a good habit to acquire.

Additionally, a properly paranoid user won't use elevated privileges at any point in the installation process. Instead they will choose to install into a directory where their unprivileged user has the required write access (eg. with local::lib, perlbrew, etc.). That's probably as much mitigation as the average user will ever need or accept. It's always a trade-off between security and convenience after all.