After 1999 WC , ICC decided to conduct ODI world cups in every nation.
2003 -SA, 2007 - WI, 2011 - Ind/pak/SL 2015- Aus / nz
Now 2019, again it went to England. before that, most wc held in england and not moved to any other nation.
For india and Aus, Feb - mar is the right time to conduct matches like wc. For england ,from May end to Sept 1st week is the summer season and all the worlds in england held in england May end to July 1st week.
Similarly this world cup also , the same calendar date has been scheduled and nothing wrong from bcci or ICC
Usually , it won't rain this much in england and last yr ind went to eng also all the matches held without affecting rain.