"The second reason is that middleware is so hard," Rymer added. "You have to invest at such a high level. It changes constantly and they could just not keep up."
Then again, if SAP buys a middleware company now, SAP would arguably be fighting a market battle that has already been waged and largely won, Rymer said: "They should be looking at the next hill."
The company's recent focus on in-memory database technology represents such an opportunity, he said.
Another observer took a different view, saying middleware is too crucial for SAP to neglect, particularly given the company's vast size and the needs of today's customers.
"If you don't have your own tools, you're dependent on someone else," said Ray Wang, partner with Altimeter Group. "Is SAP going to become dependent on IBM or Microsoft? It's a strategic asset they have to own."
NetWeaver has been improved over the years, "but it still doesn't cut it," Wang said.
It works for companies' basic requirements, "but as you get into a lot of heterogeneous data, and get outside the SAP world, that's where you see some of the challenges," he said.
There are other potential middleware targets for SAP, with a popular pick being Tibco. SOA Software is another possibility, Wang said.
Many large SAP customers are already using software from these vendors "to take care of the things SAP can't do," he said.
Still, SAP has made significant advances in NetWeaver of late, and may decide against an acquisition if it feels the right level of functionality is within reach, Wang said.
Then there's the question of cost. Software AG could represent a fairly sizable investment for SAP, as it had revenues of €847 million in 2009.
But new product lines and other innovations can no longer provide software vendors with the type of steady growth shareholders demand, Wang said.
"The shift has occurred. Oracle and IBM have proven you need to make large acquisitions in order to grow. It has taken SAP a while to realize this," he said.
But SAP users could get anxious if the acquisitions don't better their experience, he added. "This kind of money could be spent on making the [existing] products better. There could be some kind of backlash if they make a lot of these [acquisitions] and the products don't improve."