On the contrary, from a player's point of view, the difference betwen 1.5.2 and 1.4.7 is drastic. 1.5 was an update with pretty significant gameplay changes in vanilla, with an ore in the nether (finally) and several new redstone-related blocks and mechanic, especially hoppers. As a Tekkit player, the change was even greater. Not just a new pack, but a new direction for Tekkit, with previously essential mods being replaced. The time between Tekkit Lite 0.6.5 and Tekkit 1.0.0 as well as the hype built up surrounding the latter packs release contributed as well, so, um...
...yeah. Just sayin.