If "employing someone should really be a long term commitment from both parties," then employers need to start treating it as such again. Right now this is simply one among many, many imbalances between employees and employers: the loyalty demand is, in my view, a one-way street.
Employees are not to expect long-term loyalty style commitments from employers these days. Training, retirement investment packages, career paths and other intangibles that make a long-term commitment at a single employer potentially a good move don't exist anymore (at least not in any significant numbers).
Long-term investment with a single employer carries risks for the employees: opportunity costs, skill stagnation or over-specialization, far lower long-term compensation without internal "job hopping" up the management ladder (and even then it's not nearly the risk-free move it was even 20 years ago, let alone 30 or 40), etc. Employers don't acknowledge these risks the employees take, though, and simply demand loyalty without wanting to make an investment of their own other than a begrudgingly given compensation package (that is often below the actual value an employee provides).
Of course it's not fair; and that's just the way it is--it's something serial entrepreneurs and "job hoppers" should just be prepared to deal with.