Why is every patch set now a full release?

So here is the question. I have an 11g ORACLE HOME that was built as 11.2.0.1. Now if I want to upgrade to 11.2.0.2 or 11.2.0.3, I guess there is no easy way to upgrade the existing ORACLE HOME. Why didn't Oracle give the option to just apply a patch (opatch) and upgrade to 11.2.0.2 (or .3). For a customer to create a new ORACLE HOME is just a lot of work and breaks a lot of things. We have to copy over so many configs from the old home to the new home.

I'm sure there is a good reason, I'm just trying to understand what they are.

The answer has many aspects.

Install into your existing ORACLE Home

First of all you can still install the new patch set (which is now a full release since Oracle 11.2.0.2) into your existing $ORACLE_HOME. But you'll have to detach your current home from the OUI's inventory (Oracle Universal Installer) first. Please see slide 41 of the Upgrade and Migration workshop deck. Please backup the contents of $ORACLE_HOME/dbs and $ORACLE_HOME/network/admin first as you'll have to copy them back later.

$ ./runInstaller -detachHome ORACLE_HOME=/u01/orahomes/11.2.0
Starting Oracle Universal Installer...
Checking swap space: must be greater than 500 MB. Actual 10047 MB Passed
The inventory pointer is located at /etc/oraInst.loc
The inventory is located at /u01/orabase
'DetachHome' was successful.
Once you've done that you'll install into your existing (old) directory.  And finally you'll copy back your dbs and network/admin files.

Why customers might use this procedure?

There are basically two reason why a customer chooses this strategy:
(a) Home naming conventions not allowing an Oracle 11.2.0.2 home and another Oracle 11.2.0.3 home
(b) Space issues
Both are valid reasons and therefore you can stay with the old strategy.

Why did we change from patchsets to full release patchsets?

Simple reason: Customers did ask us for a looooong time why we are delivering 3GB large patchsets instead of full releases. So we'd follow this wish.
And second it will decrease the overall downtime when you'd install into your new Oracle Home. If you apply patchset software to your existing Oracle Home every Oracle process serviced by that home must be shut down as well - obviously including the database(s). And furthermore if something fails you'll have to restore your OUI's inventory (Oracle Universal Installer) plus all home contents - or reinstall your previous Oracle software.

Besides that we recommend to patch this home first with important one-offs (see links in MOS Note 161818.1) and the latest PSU or CPU. If you'd do that to your already emptied old home it will simply increase again your overall downtime.