Lockeness - Evasion is obviously hax, and should be justifiably banned.
This is mainly the sentiment of the pro-complex ban group, and it's not a sufficient justification to ban Sand Veil / Snow Cloak. Serene Grace / Super Luck doubles the chance of hax; with such lines of reasoning, Serene Grace and Super Luck are also getting the ban hammer.
You may rationalize how the 20% miss chance is somehow a much worse hax crime than the 20% chance to frz something with Serene Grace Ice Punch or a 12.5% chance to crit, but you'll be a fool to not realize that these abilities fall into the same category - luck abilities that deliberately increase luck factors for the abusers. Yes, they all have "unfair" advantages - when was Pokemon ever balanced? They are Pokemon that are more well-endowed than others - deal with it.
How have we dealt with such hax Pokemon in the past? We ban the broken ones (Garchomp & Shaymin-S) and simply deal with the other manageable hax Pokemon. Garchomp is broken with Sand Veil, but one cannot induce from Garchomp that all Sand Veil Pokemon are broken. I was scratching my head when Lucaroark was justifying this complex ban by explaining how Garchomp with evasion is overpowering - that's why it is uber. SD Acrobatics Gliscor, the most relevant example in the OU scene, is MUCH slower and weaker than Garchomp - it's not hard to have multiple checks to Gliscor.
Just like any minimal hax, you could manage Sand Veil misses / Snow Cloak misses, too. The same way how CM Latias can avoid being knocked out from a critical hit or be crippled from Jirachi's Thunder paralysis or a Politoed's Ice Beam freeze by putting up a Substitute, one can provide resources to his or her team to minimize the effect of misses. One can either add a Pokemon that can take multiple hits from Gliscor or Mamoswine for instance, so a single miss wont translate to death. Another option is to hold multiple checks to such mons, so if 1 is taken out by a freak miss it's not an instant loss. There's also a matter of adapting to such playstyles. The best way to defeat these monsters is to never let up on the offensive pressure. Go out 100% offensive so that Gliscor would never have a Substitute and a Swords Dance boost at the same time. Learning how to build teams or adapting one's battling behavior to adapt to such strategies is hax management, which is an essential skill in competitive battling.
Also one can minimize the chances of a miss due to Sand Veil by using more accurate moves, so such decision to use more accurate moves over powerful moves also applies here as well.
Thus, no, a Sand Veil miss is not totally out of your control; it is just as managable as a paraflinch hax from Jirachi.
Sand Veil miss is hax, but hax is part of competitive battling - we deal with it. It is an important skill to practice damage control when hax strikes, otherwise you would be losing to more than Sand Veil misses. Banning such minor inconveniences would only add
unnecessary ruleset to the metagame. Even more, it hampers the viability of non-broken Pokemon like Sandslash or Cacturne, which is absurd, since bans and clauses are supposed to prohibit or restrict the use of broken elements.