There are issues with moving the park entrance to where the monorail depot is.
1) AT isn’t a circular park, it’s U shaped and currently you enter at the bottom of the U so guests filter in two different directions. If you move the entrance you end up with a lot of guest filling into a bit of a dead end with only one way to go.
Its more of a backwards G, with that location bringing people in at the spur of the G. A new gate would be much nearer to the hotel area in this scenario, with more resort activities, better retail etc. by the hotels; and room for a couple more attractions around and/or replacing Galactica.... pulling people into that area. Some people would opt for straight on, using the Skyride into two other areas of the park. Those turning right, would head to Duel etc... ideally with a new attraction there too...
Potentially, crowds would distribute just as well from that location as the Tower Street entrance, but it needs investment to encourage people to specific areas.
2) The paths round that area are quite narrow for a theme park with nowhere to widen due to the topography.
I often think AT could smooth out some of their paths in key places. Many of the slopes are more aggressive than they need to be, just because AT did not make cuttings or averge out slopes to reduce gradients.
The Skyride station could have its basement level buried and be made the new ground level to greatly improve access, and the toilet and staff facilities be relocated. There are unused buildings making the paths around FV narrower then they could be. The hills are tricky, but lots of other parks have them.
3) Towers street is very close to the village, they won’t get much approved to be built in the area so it will be a lot of space with little practical use.
Many large theme parks have more than 1 entrance. The existing one could be retained, but would cover Taxis, Coaches and nostalgic people. AT land area is bigger than Disneys Animal Kingdom park IIRC, which is often claimed to be the Worlds largest Theme Park after all!