Windows 10 Photos App - no Outlook Share option??

Absolutely correct. The glaring deficit it not being able to share from Photos, and for that matter Edge, to Outlook O365. You would think that Microsoft would think that this was important on a PC. 

People writing that Android is getting better are also right. Ironically the Microsoft apps on Android do not have this problem. The options for sharing a photo from Outlook for Android are quicker and more flexible than on a PC. Right down to offering to reduce the image size.

that was not the question we know it uses mail but we want to use outlook

I think you're over-reacting somewhat...Android doesn't even come close to Windows mate, sorry, not even remotely. Windows has some issues but you're comparing a single grape with a pineapple, no comparison. I am actually kinda shocked they haven't addressed this yet.

With Google Picasa taken off the shelf, you'd think MS would go hard on this app to take the photo management market but it seems they don't really care too much about it.

Recently replaced a 12 year old desktop with a newer, faster computer, with Windows10 and Office 2016.  What a disappointment.  This share issue, it's general refusal to accept Outlook 16 which I paid big $$ for as it continues to push me to it's mail app.  To everyone on this board...Android computers are getting better and better every day,  I which I'd considered one.  I realize it doesn't help if its a company computer, but for personal use.  Microsoft is losing the race, and losing my business.

Problem is Microsoft sat on their rear end thinking they were the bees and knees of operating systems and quietly android was creeping up on them. BOO and they made a mad rush playing catchup and in some areas have failed miserably.

Why outlook 365 cannot be made the default email for my computer and then work with all the programs and apps is astoundingly stupid.

Microsoft don't, I think know how to fix it, perhaps if they asked Alphabet/google they might make some progress.