There is no issue with orphans, sure there will be more orphans, but the orphan rate is the same for all miners, so it ends up fair and business as usual.
Since there's no issue with orphans, altcoins does not need to deal with it, it's a non-issue. As you already mentioned, Litecoin operates just fine, with 2.5 minute blocks, no complaints from litecoin miners about orphans neither.
Block overhead is a non-issue, litecoin blockchain size is tiny compared to Bitcoin, even though it has nearly 3X more blocks. Transaction data takes up more disk space by far. A solution will need to be developed for the fast growing disk space usage anyway, faster blocks has nearly no impact on the disk space issue.
Faster blocks is 100% the superior solution, exactly 0 user ever said "nooo, my 1st confirmation came too fast".
I'm not even sure why bigger block size was chosen over faster blocks. Maybe it's arrogance, and not admitting altcoins got it right (faster blocks being superior).
It's possible, but doesn't help scalability. If there are ill effects due to full blocks, making them twice as frequent won't really help.
Full blocks? I don't understand why they would be full after doubling? Perhaps I wasn't clear in what I am asking. When I suggest cutting the reward time in half from 10 minute targets to a 5 minute target I am not saying to also cut the block size in half. The block size would still be the same size but since a block is made twice as often then this would effectually double the blocksize.
Already blockchain is in gbs. If they implement your proposed way of reducing reward time by half every 4 years then we need piles of tbs of hard disk just for blockchain.
What percent of a block is for non-transaction data? That would be the only increase in total blocksize since the number of transactions are determined by the "market" and the transaction volume. Processing the transactions in half the time should only increase the total of non-transaction data shouldn't it?
But, ok, we are getting a list of issues that would be affected and that's why I was asking. The first item in the list was that there would be an increase in the number of orphaned blocks and then I asked how other alt coins that have quicker reward times handle that problem. Haven't gotten any answers to that question yet and am curious if that is still a legitimate reason or not.