The days of starting a career at one company and then retiring on a pension plan from that same company years later are gone. I remember starting for a corporation that had both a 401k and a retirement. I planned on being there until retirement and cashing in on both. 10 years, 4 company name changes, 2 ownership changes, and 1 company bankruptcy later; the retirement fund is gone and the I get a letter in the mail telling how the company was going to change the management of 1 of the two 401k's I had and letting me know how they would re-invest my money, including some purchase of their stock. No thank you, I prefer to invest based on my personal needs. In short, I don't think that the best intending company could possibly know the personal needs of every employee they have.
Statistics say that the average person will change jobs 8 times during a their career. This merely highlights why you would need a private savings plan in addition to your company matched 401K. You want to take full advantage of pre-tax matches, but if you are changing jobs there is likely a reason. If that reason even remotely resembles concerns about financial impropriety you need to seperate you finances from theirs in short order.
If any of these resembles your financial situation contact YOUR financial planner. If you don't have one feel free to contact me, but take care of today so that tomorrow will be easier.