that is your opinion, so fair enough.
note, however, that i'm not suggesting a reduction of the cost of dagger or the introduction of cheap blink consumables! to get the ability to blink people would still have to farm at least 2150 gold just as before!
just consider the amount of tp scrolls a player buys throughout a game. in many games it can reach 20 per hero which is equivalent to the cost of a dagger. furthermore, the fact that tp scrolls (as consumables) exist is just a testament to how important and useful teleportation is through every stage of the game. not to mention that in order to get BoT (the actual item that gives the teleport ability similar to dagger that gives the blink ability) players must 'endure the same long duration of farming' as its recipe costs exactly as much as dagger does (or even more if we throw in the 500 gold for the boot component of the BoT recipe).
i guess you can argue that i can't really compare teleport to blink, and that is a fair argument as they are different skills. they do, however, fulfil a similar purpose: provide mobility. they just achieve that in two different ways, both of which are equally useful imo. that is why i don't see the problem of having both abilities on boots that also cost the same amount of gold.
it would be a tradeoff between BoT and a dagger (2 slots) or kelen's slippers and tp scrolls (2 slots again).
then again, even now dagger is not exactly easy to farm (especially on those heroes that could make the most use of it). so i can't really imagine shaker, tide and sand king roaming around the map with blink boots at the 10 minute mark...
i don't know, once again i can understand your argument, but i also think that my counter argument has some worth. all this recipe does is give 20 ms and a free slot.
now, the free slot is a big thing granted, but most of the time heroes (especially those who benefit most from dagger being roaming gankers or support) don't get enough farm to fill all their item slots anyway. furthermore, 2650 gold for boots (even with blink) is not a price to laugh at. finally, everyone who chooses to get blink boots would have to sacrifice the global mobility (and higher ms) of BoT or the invaluable strength boost from (the cheaper) threads early game. so as you can see, this wouldn't really be the best boot type in all situations for all heroes.
it would merely be another option of late game luxury footware to choose from to act as competition for BoT, depending on the players' playstyle and the needs of the game.