focus.com
That's an oversimplification, but it sums up what the general thinking should be.
"6. IT support requirements are siphoning limited resources away from my organization’s core business activities."
Even if your main business is in the IT field, supporting it is always going to siphon away resources without directly generating revenue (unless you happen to sell support contracts, and even then your INTERNAL IT support is pure overhead) and those resources are always limited.
A more useful phrasing would be: "IT support could be more effeciently and cost effectively provided by another company."
This is certainly true for many companies, but also certainly not true for others.
This statement though is a good one: "9. Our business needs do not require extensive or frequent customization of critical software or services."
If all of your needs could be met by off-the-shelf software without extensive adjustments then Saas is probably worth looking at.
The bottom line is that SaaS is excellent for many situations and is often worth serious consideration, it can often save considerable cost for one thing. But it also comes with many trade offs and drawbacks. It will be appropriate for some companies and not for others.
For the immediate future that balance will likely continue to shift more and more heavily towards SaaS, but where the balance point will land remains to be seen.