Will data exporting/importing limitation be lifted off the express edition in a near future?

They will not remove the restriction as they have no reason to. The only reason they let you export the first 50 rows is so that you can try it, and therefore buy the standard or up versions to use this functionality. Really though if your just looking to use it for this data import export functionality and not any of the extra functionality that the upgrade versions can offer.

There are no limits to export/import files in .csv format === There are limits to export/import data in other formats

There are no limits to export/import files in .csv format. Other unlimited file formats are available in Standard, Pro or Enterprise Editions in Imp/Exp Wizard.