Advantages of spinoffs
Spinoffs can hurt bondholders if the debt covenants are weak and allow the company to spin off significant assets backing the debt. This benefits the equity as the spin-off that is unencumbered with debt can issue debt at lower rates.
Spinoffs make a company easier to understand and allow more institutional investors to own the stock (e.g. sector/industry-specific funds). This may increase the share price. This can generate value if the stock is used as acquisition currency in rolling up poorly-managed companies (e.g. LBYTA).

