I have worked with several Enterprise level clients over the past few years that have gone from on premise to cloud. My observation is that it's a better value proposition for small companies than big ones.
First, the good news:
1) With cloud based systems, the vendor generally takes care of backups, disaster recovery, DB & OS patches, etc.
2) Cloud vendors offer redundancy. Data is synched between data centers so if your main DC goes down you will be back up with little to no interruption.
3) With cloud vendors you can very easily scale up, or down, based on demand.
Now, the bad news:
1) When you move to a cloud system you are essentially a tenant, along with a bunch of other companies. You no longer entirely control your servers and software.
2) Scheduled downtime (for patches, backups, etc.) are done on the vendor's timeline - not yours. You lose the ability to put off non-essential system updates.
3) Most of the cloud based Enterprise level systems I have worked with (ex. Workday, Oracle Cloud) do not provide the ability to customize the application using custom code. On premise systems, such as PeopleSoft and SAP, do provide this capability. For some companies, this is a deal breaker.
4) While the cloud may seem less expensive at first, in the long run it's probably going to cost you more. Think of it as renting vs buying a house. This is why Adobe and Microsoft and Oracle have jumped into subscription software. It is more profitable for them.
5) Pricing. With AWS, for example, you have to be very careful about how you use resources. Otherwise you can end up really overspending. On premise licensing is typically much more straightforward.
6) If you are a big company, you already have the big beefy servers and redundant data centers. Audit and compliance procedures are already in place. Smaller companies are not likely to have this and are willing to accept the compromises.