Why are there so many express and long-distance trains to or from obscure locations like Manduadih, Habibganj, etc.?

Often, the terminus for long-distance trains into a city or town is not the railway station that is the "main" station for that town, but rather some outlying or suburban station that can better handle the long-distance traffic. The names of the trains, unfortunately, often reflect these actual termini rather than the "real" destination to which service is being provided. Similarly, sometimes a nearby station is used for services to an intermediate city as well, instead of a station at the city. For e.g.

• New Delhi services may terminate at Hazrat Nizamuddin or Sarai Rohilla.
• Mumbai services may terminate at Dadar, Kurla, or Bandra.
• Bhopal services may terminate at Habibganj.
• Calcutta services may terminate at Howrah or Sealdah.
• Chennai (Madras) services may terminate at Egmore or Tambaram
• Varanasi services may terminate at Manduadih.
• Jaipur services may terminate at Durgapura.
• Hyderabad services may terminate at Kacheguda.
• Ranchi services may terminate at Hatia.
• Nagpur services may terminate at Itwari.
• Patna services may terminate at Rajendra Nagar.
• Bangalore services may terminate at Yeshwantpur [5/01]

Similarly, for intermediate stations:

• Kazipet for Warangal
• Shrirampur for Belapur
• Katpadi for Vellore
• Pratapnagar or Vishwamitri for Vadodara (Baroda) (NG)

Source - IFRCA.org