I just thought you were supposed to only have one application per VM
While there are certainly some applications, services and roles, like Exchange Server, that should run on dedicated machines (whether virtual or physical), that's not to say that all applications, services and roles should be run in their own silo.
That being said, I don't see anything inherently wrong with running WSUS and SEPM on the same VM. Neither one is particularly resource intensive. One definite advantage to virtualization is that you can, if necessary, quite easily scale up if it turns out that either of those roles needs more resources. Adding CPU, Memory and Disk resources to a virtual machine is, in most cases, a fairly trivial matter.
Additionally, with Windows Server 2012 R2 Standard Edition you are
licensed for two Windows Server based virtual machines (of the same version and edition), you are not
limited to two Windows Server based virtual machines. You can run more than two Windows Server based virtual machines but any beyond two need to be licensed individually.
Let me add this to address some of your comments to the answers provided:
It took me a long time to get on board with virtualization. Now that I am onboard with it I find very little value in or justification for "single use" physical servers these days. Even if you are planning on running multiple applications, services and roles on a single server, you can still benefit from virtualization in improved efficiencies, scalability, manageability, availability, portability, etc., etc. If you can confidently say that the applications, services and roles you've outlined in your question are all you're ever going to need and that this single physical server running all of those will do the job then by all means go for it, but I think that's being shortsighted. What happens when you decide that you need two Domain Controllers so that you're inline with Active Directory best practice (you really should deploy two Domain Controllers), or you acquire another Line of Business Application, or another SQL Server, or Exchange Server, etc., etc.? Are you going to purchase another physical server? How well is that going to scale every time you need to add a component to your infrastructure?