Coinomi was open source years ago and we had to make the tough decision of closing it. The developers still contribute to several open source projects. Reopening the source is not completely out of the question, but it's not a simple decision to make either.
That doesn't answer the question of
why it isn't open source? Why, if it was open source, did you decide to close it? You say it was a tough decision, so there must of been lots of factors you considered. What were they?
I'm sure you will always have lots of users, but serious users on this forum are never going to use and never going to recommend closed source software.
One of the major reasons for closing the source were fake or cloned apps being distributed on the app store. Even in case of "benign" clones, their developers would keep all support links and the official logos and branding. We cannot provide support for modified versions, and both malicious and poorly implemented "benign" clones were having a negative effect on our image and ability to provide quality support for users.
Small warning: Being on Github does not mean that wallet is open source and therefore safe. Unless you check each line in the wallet code or trust that there are sufficient developers who have checked each line with the code, there is no difference between the open and closed wallets.
Many scammers give a false sense of security by inserting part of the code "compressed on Github" or uploading unverified/recent files.
Always check wallet reviews before downloading it.
Exactly, having the source code open doesn't guarantee that the files you download from app stores are the same. And even if they are, it's not guaranteed that the source code was inspected by someone who knows what to look for. One of the biggest proponents of open source wallets admitted himself that no one was checking his wallet.