"enterprise software is there to ..."
I would say it's there to do for the office what machinery does for the factory floor. It's a form of automation. The problem is that a lot of it is just very badly done. Failed machines get fixed or scrapped. Failed ERP systems live on forever bleeding away time, money, and the will to live.
I think the big problem with enterprise software is the lack of tangible and measurable benefits in most cases. You know if a new factory machine has saved labour on a production line. You just have to count the number or workers and compare that to output. ERP and CRM systems often seem to get installed with no clear goals or way of measuring the result.
As for the size of firms, the reason why the largest companies tend to be the big customers for "enterprise" software is that the benefit of this software is often so small that you need large economies of bureaucratic scale to see any net benefit from the up-front cost of implementation and the ongoing license fees. When someone figures out how to do this sort of thing quickly and cheaply, we'll see it filter down more to smaller businesses.