DOes PLM help business? It can, just look at those who've successfully implemented such. However, it's not a panicia. Just like its cousin ERP you can really mess up what was working for your company.
There are a lot of companies the worse for it that jumped onto the SAP bandwagon. Had they either taken the money invested in ERP and put it in a CD or the stock market the company would have been ahead or had they invested more time looking at what implementing ERP really means. Unfortunately in most corporations today implementation really means installation and customization of the S/W not looking at the whole picture of determining if, how, when, what and where these technologies should be implemented.
PLM is no different. If you have a simpler lifecycle than the model that you're S/W supports you're going to waste a lot of Engineering time just operating the S/W for next to no real benefit to the corporation.
The next issue is does your Engineering Department really employ PLM methodologies and practices. Several years ago I did a process audit on a engineering department that was touting to their management that they used "System Engineering" methodologies to ensure delivery of high quality products. Their customer had asked for the audit. What was found was a serious disconnect between what management, engineering and customer thought were best of breed "System Engineering" practices. If I was to give them a CMMI level rating it would have been a Negative 1.
While they had all the nice S/W, policies and practices documented no one was trained on using them, people where using all sorts of work arounds to avoid using or by-pass the controls in the S/W that structured the process.
When I have looked into various shops putting in PLM I'm seeing the same issues arise. S/W installed, customizations put in place to by-pass the process. In other words you might as well put in a file server and get better results.
If you're going to demand results from PLM --ha-- you mean results from the organinzation implementing PLM, you'd better look to see if the PLM process is going to help or complicate issues and then really work on creating a real implementation plan beyond calling in the I.T. department to install the S/W and a one day briefing to end users that amounts to how to log on and file stuff away.