Indian Railways: Divided By Zones, United By Railfans - Karthik

While it's true that TALGO coaches are shorter in length, it's also true that they have only 4 wheels (in place of the usual 8). That's where the concept of the unconventional "Jacob's bogies" fits in. Now, if the length of coach is increased, the weight will also increase proportionally. Then 4 wheels may not be sufficient to hold the coach or else, the weight on wheels may go out of limits which the P-way or the suspension can handle (not using the term "axle load" here).
Making the coach shorter reduced the length of the rigid wheelbase, thereby allowing the coach to negotiate curves at higher speeds. Also, TALGO coaches do not have axles. Wheels are independently installed...
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and suspended. The suspension goes right up to the roof and is supported by a column. As a result, the wheels can rotate at different speeds.
This concept is unlikely to work on a 40-45 tons, 24 metres long LHB coaches. Given the weight and length, the coach would require 8 wheels. Where will those columns be installed for supporting 4 extra wheels?
TALGO coaches can work on different gauges too (broad gauge, standard gauge etc), which makes them highly adaptable. The presence of all these features is what made IR to go for TALGO in the first place! :)