Why is the FA Cup so special? There are a few reason, but certainly, "A chance to play at Wembley" will be one of the most popular reasons given by players and fans alike. Playing at Wembley has a special charm. The venue is only used for a few select matches including England National Team games, the FA Cup Finals and the play-off championships of the lower leagues, so it is a great honor when one's team is involved in a match at the stadium.
Nepal's Wembley - Dasharath Rangasala, lacks that charm. On the contrary, it's hard to find a Nepali footballer of any ability who has not played there. Just in the last few months everything from the Pepsi 7-A-Side to the B-Division to the qualifying rounds of the Coca-Cola School Tournament have been held there. As a result there isn't anything special about Rangasala these days: playing there is not special; watching a match there is not special. If anyone is curious as to why attendance at football matches is declining, that is one of the key reasons.
There were no alternatives in the past, but now with the two ANFA technical centers in Sadobato and Chyasal, there really is no need to play minor matches at the national stadium anymore. Save Rangasala for the big occasions. When a player or fan goes to the stadium, it should be a highlight of their life.