PEAR support is still very experimental, and is not required during install or upgrade.
And I also do not wish to use console pear installer(because it requires root)
We have embedded PEAR client into Magento and it does not require root permissions nor pre-installed PEAR on the host.
For people that PEAR install/upgrades don’t work for any reason, there’s always an option to overwrite the files with unpacked complete package.
Due to the nature of Magento’s upgreadability and customization concept, this method should not overwrite correctly written custom themes and modules.
For automated script to update multiple installations this method could also be more convenient than PEAR